Implement Deltas-only copying of configurations in JbossAsControlCreateConfigurationMojo

From Antony Stubbs:

The other thing I noticed is that the JbossAsControlCreateConfigurationMojo doesn't seem to perform a delta copy as ALR has mentioned in places, but instead copies the entire directory every time and overwrites existing files. Is this a feature worth pursuing? It took quite a long time (at least 60 seconds) copying the config directory on every invoke for me - i.e. it appears worth it to me.