Caching of ProjectState objects.

Made the existing constructor of ProjectState private, and created a new
named constructor which caches the instances of ProjectState. This ensures
that no two identical ProjectStates will exist.
Unit tests of ProjectState

Testing for equality and that caching of ProjectState object instances
works.
Using cache of ProjectStates for xstream deserialization.

Implemented the readReslove() method in ProjectState, such that the
cache is used when objects are deserialized by xstream from disk on
jenkins startup.
Add feature: support two repo sync's options

- current branch option(-c) is fetch only current branch from server
  if this option is enabled, sync operation will be more faster
- quiet option(-q) is more quiet. you can't see tag and branch information
  if this option is enabled, log file will be more smaller
Corrected identation
Improved wording of help text

... for current branch and quiet repo options.
Updated roadmap
Bjarke added to maintainers and copyright notice
[FIXED JENKINS-14926] Implement the parent interface's getAffectedFiles() method.
New Known Bugs file
Allow localManifest to be specified either literally or as an URL.

Check the beginning of the localManifest field.  If it starts with
legal XML preamble <?xml then use it literally.  Otherwise assume
it is an URL, and fetch the URL.
Enhance comments and help for localManifest
[maven-release-plugin] prepare release repo-1.3
[maven-release-plugin] prepare for next development iteration
Add support for repo group command (repo init -g)
Merge pull request #14 from vsiva/repogroup

Add support for repo group command (repo init -g)
Switch pom.xml from hudson to jenkins

hudson is semi dead and doesn't build with jre7
implement ui for --repo-url
adding myself as maintainer

so people know who to poke
[maven-release-plugin] prepare release repo-1.4