Optimization: Reduce number of queries to DB

Using PostgreSQL as backend, logging the DB statements, there seems to be quite a number of queries just to display a single Resource page with a single WMS Resource like `GET /?lang=en&resource_type=OGC%3AWMS`:

```
LOG: statement: BEGIN
LOG: statement: SELECT t.oid, typarray
FROM pg_type t JOIN pg_namespace ns
ON typnamespace = ns.oid
WHERE typname = 'hstore';

LOG: statement: ROLLBACK
LOG: statement: BEGIN
LOG: statement: select version()
LOG: statement: select current_schema()
LOG: statement: show transaction isolation level
LOG: statement: SELECT CAST('test plain returns' AS VARCHAR(60)) AS anon_1
LOG: statement: SELECT CAST('test unicode returns' AS VARCHAR(60)) AS anon_1
LOG: statement: SELECT 'x' AS some_label
LOG: statement: ROLLBACK
LOG: statement: BEGIN
LOG: statement: show standard_conforming_strings
LOG: statement: SELECT resource.identifier AS resource_identifier, resource.resource_type AS resource_resource_type, resource.title AS resource_title, resource.url AS resource_url, resource.latitude AS resource_latitude, resource.longitude AS resource_longitude, resource.owner_identifier AS resource_owner_identifier
FROM resource
WHERE resource.resource_type = 'OGC:WMS'
LOG: statement: SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier ORDER BY run.checked_datetime ASC
LIMIT 1
LOG: statement: SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier ORDER BY run.checked_datetime ASC
LIMIT 1
LOG: statement: SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier ORDER BY run.checked_datetime DESC
LIMIT 1
LOG: statement: SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier ORDER BY run.checked_datetime DESC
LIMIT 1
LOG: statement: SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier ORDER BY run.checked_datetime DESC
LIMIT 1
LOG: statement: SELECT count(*) AS count_1
FROM (SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier) AS anon_1
LOG: statement: SELECT count(*) AS count_1
FROM (SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier AND run.success = true) AS anon_1
LOG: statement: SELECT "user".user_id AS user_user_id, "user".username AS user_username, "user".password AS user_password, "user".email AS user_email, "user".role AS user_role, "user".registered_on AS user_registered_on
FROM "user"
WHERE "user".user_id = 1
LOG: statement: SELECT count(*) AS count_1
FROM (SELECT resource.resource_type AS resource_resource_type
FROM resource) AS anon_1
LOG: statement: SELECT resource.resource_type AS resource_resource_type, count(resource.resource_type) AS count_1
FROM resource GROUP BY resource.resource_type
LOG: statement: SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier ORDER BY run.checked_datetime DESC
LIMIT 1
LOG: statement: SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier ORDER BY run.checked_datetime DESC
LIMIT 1
LOG: statement: SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier ORDER BY run.checked_datetime DESC
LIMIT 1
LOG: statement: SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier
LOG: statement: SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier
LOG: statement: SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier
LOG: statement: SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier
LOG: statement: SELECT count(*) AS count_1
FROM (SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier) AS anon_1
LOG: statement: SELECT count(*) AS count_1
FROM (SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier AND run.success = true) AS anon_1
LOG: statement: SELECT count(*) AS count_1
FROM (SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier) AS anon_1
LOG: statement: SELECT count(*) AS count_1
FROM (SELECT run.identifier AS run_identifier, run.resource_identifier AS run_resource_identifier, run.checked_datetime AS run_checked_datetime, run.success AS run_success, run.response_time AS run_response_time, run.message AS run_message
FROM run
WHERE 2 = run.resource_identifier AND run.success = true) AS anon_1
127.0.0.1 - - [19/Dec/2016 21:34:41] "GET /?lang=en&resource_type=OGC%3AWMS HTTP/1.1" 200 -
```

This happens behind the facade of SQLAlchemy I guess. Possibly some statements in https://github.com/geopython/GeoHealthCheck/blob/master/GeoHealthCheck/models.py in combination with the templates may be optimized.