Various minor tweaks and enhancements

Hi Sandeep,

I noticed some issues under load testing which I've now fixed.  They were minor bugs which probably wouldn't have an effect on code written against your original API as long as that code didn't look for specific exceptions when setting and getting.

I've also made an enhancement that allows setting the exhausted strategy and changed some of the logging.  There were a few too many messages coming out at the info level so I changed many of them to log at the debug level.  Once things pass QA I'll submit to the central repository and then I think we should update the wiki page and maybe do a little promotion.  Maybe the guys at Yammer will be interested in picking this up for dropwizard.  There are tons of people looking for something like this on stackoverflow, so we should probably also respond to some of the discussions there and let people know that this is now up on the central repository.  We might also want to generate the JavaDoc and post that somewhere.