Release 0.4.4

Bumps Java driver version to 2.12.1 - a recommended update for all users.

Release 0.4.3

• change default Clojure version from 1.5.1 to 1.6.0 (we still support back to 1.3.0)
• update Java driver to 2.12.0 to support MongoDB 2.6.0
• support :write-concern on mass-insert!

0.4.2

Library updates. Switch default version to 1.5.1.