Create databases during shard creation

**Issue by [jberkus](https://github.com/jberkus)**
_Thursday Dec 04, 2014 at 22:34 GMT_
_Originally opened as https://github.com/citusdata/pg_shard/issues/3_

---

Currently the user has to manually create databases on each worker to match the master. Since we require that the database names match anyways, and there are no real options here, we should just have master_create_worker_shards create the databases on workers if they don't already exist. Probably we should do this by connecting to the "postgres" database first, which would then require some extra error handling.

Start at the master_create_worker_shards entry point and trace how it connects to workers. The issue proposes connecting to the postgres database first and creating the matching worker database when absent; done means shard creation no longer requires manual database setup on each worker, with the extra connection errors handled.

Written by the indexing model from the issue text.