(MODULES-661) Add host parameter to psql commands

[petems]

This allows you to use postgres_pqsl commands to be run against a specified host. The ultimate goal being that you can use puppetlabs-postsgresql to run against remote instances, especially things such as Amazons RDS service.

This PR will be further extended to do things like allow remote table_grant and the like.

[underscorgan]

👍 thanks @petems

[ColinHebert]

Unless I'm mistaken, this still assumes that there is a user (defined with :psql_user) on the machine with passwordless access to the database.

[petems]

@ColinHebert Yes, right now it was a very MVP implementation, I'm breaking up the larger "Use the postgres module to fully provision a remote instance" into smaller chunks.

@tomhey's done some awesome work around adding a new connection_options hash using Postgres Environment variables (http://www.postgresql.org/docs/current/static/libpq-envars.html) which makes this a lot better, and is probably the best approach to properly implement it. Discussion's here if you're interested https://tickets.puppetlabs.com/browse/MODULES-661