Config search path

[dividedmind]

This patch allows overriding postgres search path in app config.

Rationale: while search path can sometimes be used to good effect to isolate apps on a common database without them being aware of it (hence only setting them in database config), at other times the app has awareness of the schema and manipulates them directly - in these cases, the schema can be a part of the app, not the database, configuration.

[JonathanTron]

thanks for the PR, I'll have a look later today, and will merge it.

[dividedmind]

Thanks. BTW, I didn't have JRuby at hand, so if you do I'd be grateful if you could check if it works as intended.