Add new commit msg format to README

Adds a description of the new commit message format as well as examples
of well formatted commit messages to the README.md.  This is required
to enable developers to quickly identify what the commit is intended to
do and why the commit was added.
ha policy changes and refactoring

This patch abstracts the different HA policy configurations into their own classes. This avoids having unrelated configuration elements in the same configuration class or xml chunk.

Because of this the HornetQServerImpl class has been simplified by extracting the different Activations into their own class and moving into the Activation any code that is specific to the actual Activation. This should make it easier to extend or add any new Activation code.