REP-516 Improve Module Read-Me's
Added and/or Updated the Descriptions in the POM's dealing with the Datastore component including those about exposing a Datastore as a Service for distributed use.
Replaced some text that had been inadvertently removed from a POM description.
Updated all of the POM descriptions based on review comments.
Merge pull request #975 from rackerlabs/REP-516

REP-519 Improve Module Read-Me's