Checkpoint commit for OPENDJ-1174 Transfer responsibility for populating the ChangeNumberIndexDB to ChangelogDB


Properly implemented the medium consistency point algorithm.


ChangeNumberIndexer.java:
Renamed instance field previousCookie to mediumConsistencyRUV and mediumConsistencyPoint to lastSeenUpdates.
Added mediumConsistencyCSN instance field.
Changed newCursors from ConcurrentMap<Integer, DN> to ConcurrentMap<CSN, DN>.
In tryNotify(), removed CSN parameter.
Added methods canMoveForwardMediumConsistencyPoint() and moveForwardMediumConsistencyPoint().


ChangeNumberIndexerTest.java:
Updated to reflect how the medium consistency point algorithm should work.

MultiDomainServerState.java:
Renamed get() to getCSN().

ServerState.java
In update(), updated javadocs + renamed local variables.