add entities and DAO for announcements resource.
and mongo access for announcements.
add announcements resources and encoders
Merge pull request #136 from matthesrieke/feature-announcement-resource

Feature announcement resource
moved JSON keys to constants class; added id to ToU instance
announcement validation
terms of use validation
Merge pull request #137 from autermann/schema

very nice!
Merge pull request #11 from enviroCar/dev

Dev