Merge pull request #189 from jasobrown/master

switching to not using guava 12 methods
Merge pull request #190 from jasobrown/master

rev number fix
in response to https://github.com/Netflix/Priam/issues/15 added a more friendly error message
Merge pull request #193 from spencergibb/rac-check-in-new-token

friendly error message when aws AZ not in list of AZ's.

LGTM. Thanks!
followup to Priam-193 pull request, switching to String.format for the log message.