Add logback support

[sam]

Traditionally logging support was added by adding a :logger accessor to your class, and instantiating your class through Harbor::Container so that it would be assigned a Logger instance for you.

This methodology should be deprecated in favor of adding a Loggable module to Controllers, and allowing you to include it into other arbitrary classes.

Then we need a simple, unified configuration interface for logging that accomodates using rjack-logback under JRuby, and stdlib's Logger on CRuby.