Frequent Invalid Response errors seen in LogEntries for API App

Over the last few weeks the api application in heroku has been experience higher than normal response times and higher than normal memory usage.

When looking at looks I see frequent and consistent application errors as follows. We should clean these errors up. Unsure if the errors and the load are correlated at this point but these are worth cleaning up. We haven't heard anything from users of the application concerning these.

From LogEntries:

```
13 Jan 2019 10:13:53.831409 <158>1 2019-01-13T15:13:53.336566+00:00 heroku router - - at=info method=GET path="/ember/2.16/namespaces/Ember.String/methods/htmlSafe?anchor=htmlSafe" host=ember-api-docs.herokuapp.com request_id=3b57b253-6b3b-4077-b78e-46c0795cad64 fwd="66.249.64.31, 54.224.194.227, 157.52.99.51,157.52.79.44" dyno=web.1 connect=0ms service=423ms status=307 bytes=342 protocol=https
Heroku/Syslog drain
13 Jan 2019 10:13:53.977431 <158>1 2019-01-13T15:13:53.248446+00:00 heroku router - - at=info method=GET path="/ember/2.15/classes/Ember.CoreView/methods/decrementProperty?anchor=decrementProperty" host=ember-api-docs.herokuapp.com request_id=e2f6706c-4628-449b-8f8f-97d8b23e01df fwd="54.36.148.181, 54.224.194.227, 157.52.99.35,157.52.79.38" dyno=web.1 connect=0ms service=1233ms status=200 bytes=314001 protocol=https
Heroku/Syslog drain
13 Jan 2019 10:13:57.875280 <190>1 2019-01-13T15:13:53.226937+00:00 app web.1 - - { FetchError: invalid json response body at https://ember-api-docs.global.ssl.fastly.net/json-docs/ember/2.16.4/namespaces/undefined.json reason: Unexpected token < in JSON at position 0
at /app/tmp/deploy-dist/node_modules/node-fetch/lib/index.js:247:32
at process.internalTickCallback (internal/process/next_tick.js:77:7)
Heroku/Syslog drain
13 Jan 2019 10:13:57.875104 <190>1 2019-01-13T15:13:53.226953+00:00 app web.1 - - message:
Heroku/Syslog drain
13 Jan 2019 10:13:57.875272 <190>1 2019-01-13T15:13:53.226954+00:00 app web.1 - - 'invalid json response body at https://ember-api-docs.global.ssl.fastly.net/json-docs/ember/2.16.4/namespaces/undefined.json reason: Unexpected token < in JSON at position 0',
Heroku/Syslog drain
13 Jan 2019 10:13:57.875178 <190>1 2019-01-13T15:13:53.226957+00:00 app web.1 - - type: 'invalid-json' } 'fetching by class or module failed, retrying as namespace'
Heroku/Syslog drain
13 Jan 2019 10:13:57.875211 <190>1 2019-01-13T15:13:53.237442+00:00 app web.1 - - 2019-01-13T15:13:53.237Z 200 OK /ember/2.15/classes/Ember.CoreView/methods/decrementProperty?anchor=decrementProperty
Heroku/Syslog drain
13 Jan 2019 10:13:57.875280 <190>1 2019-01-13T15:13:53.277606+00:00 app web.1 - - { FetchError: invalid json response body at https://ember-api-docs.global.ssl.fastly.net/json-docs/ember/2.16.4/namespaces/undefined.json reason: Unexpected token < in JSON at position 0
at /app/tmp/deploy-dist/node_modules/node-fetch/lib/index.js:247:32
at process.internalTickCallback (internal/process/next_tick.js:77:7)
Heroku/Syslog drain
13 Jan 2019 10:13:57.875104 <190>1 2019-01-13T15:13:53.277614+00:00 app web.1 - - message:
Heroku/Syslog drain
13 Jan 2019 10:13:57.875272 <190>1 2019-01-13T15:13:53.277616+00:00 app web.1 - - 'invalid json response body at https://ember-api-docs.global.ssl.fastly.net/json-docs/ember/2.16.4/namespaces/undefined.json reason: Unexpected token < in JSON at position 0',
Heroku/Syslog drain
13 Jan 2019 10:13:57.875118 <190>1 2019-01-13T15:13:53.277618+00:00 app web.1 - - type: 'invalid-json' }
Heroku/Syslog drain
13 Jan 2019 10:13:57.875194 <190>1 2019-01-13T15:13:53.335097+00:00 app web.1 - - 2019-01-13T15:13:53.334Z 307 OK /ember/2.16/namespaces/Ember.String/methods/htmlSafe?anchor=htmlSafe
Heroku/Syslog drain
```