Revision 227148

Working on: MNG-662

o Moved release.properties management to a helper class
o Created a helper class for caching/prompting for project-versions
o Created a helper class for managing SCM info updates during the release:prepare process
o Moved as many of the shared fields out of AbstractReleaseMojo as possible, given the refactor to reactorized processing
o Refactored the PrepareReleaseMojo to process a list of projects, and resolve inter-dependencies during transforms, etc.
o Refactored the PerformReleaseMojo to adjust to the new helper classes.
o Removed the old transformers, since MavenProject.writeOriginalModel() can be used instead, using the modello writer
o Bumped the maven-scm versions up to 1.0-alpha-2-SNAPSHOT, and added maven-scm-manager-plexus.