Prevent implicit close

• Don't close connection as part of done() -> we want to be able to call done to propagate any errors, but then carry on using the connection promise from a different branch of promises.

More promise methods

• Add finally method to wrap Q's version

Misc Fixes

• Fix implicit close performed by done()
• Increase test coverage
• Ensure values returned from transaction propagate to next then clause after transaction
• Ensure errors thrown in transaction propagate to next fail clause after transaction

v0.4.0

Initial release of db-connection-promise

• Full rewrite of any-db-q
• Implemented "chain" API (IE: returning object that .query and .then can be called upon, rather than having .query return a promise)
• Made DbConnectionPromise class which adhears to Promises/A+ specification