Re-implemented "makeReleaseVersion" as a custom (enhanced) task.

Included in this change is a rename of the versionFile extra property:
  versionFile -> versionPropsFile

Also included some comments and minor formatting changes.
Added release and distribution tasks.

I've added 3 new tasks for creating and releasing distributions:
	
	1. createDistribution -- this adds a dependency on the war plugin which
is a little problematic, it seems, since all subprojects will need that
plugin.
	2. backupReleaseDistribution -- backs up the previous dist.
	3. release -- currently does nothing except log; has a dependency on
backupReleaseDistribution.