Add support for versioned documents
Add support for ?version=diffs
Clean up existing versioning functionality
Add version number to response in write requests
Closes mongodb connections in tests

Before, for each app the connection was kept open. This could cause
problems if the server wasn't configure to support as many connections
as testss.
Javier Gonel
ulimit not needed anymore. See #283.
No need to increase ulimit on most systems.
Merge branch 'graffic-tests-mongodb-connections' into develop
rst/sphinx header
Fix failing unit tests
Merge branch 'develop' into versioning
Add test unit plan for versioning
Implement TestLateVersioning unit tests
Enable version control before test data is entered
Add version controlled contacts after setUp instead
Add TestPartialVersioning write method tests and fix patch
Complete TestPartialVersioning tests
Add primary tests for TestCompleteVersioning
Add a nice error for a bad projection with a version query