add netty global boss pool
only call releaseExternalResources when not using shared pools
Merge pull request #924 from FranciscoBorges/stop-stable

Avoid stopping the replicationManager too soon
Merge pull request #925 from andytaylor/master

added global netty boss pool
HORNETQ-1155 Add static methods to avoid in-lining of constant values. Following
http://docs.oracle.com/javase/specs/jls/se7/html/jls-13.html#jls-13.4.9
Do not create new server sessions if state!=STARTED