Merge branch 'stable-2.0'

Merge branch 'stable-2.0'

By Robin Rosenberg (6) and others
via Gerrit Code Review @ Eclipse.org (2) and Matthias Sohn (1)
* stable-2.0:
  Prepare next 2.0.0-SNAPSHOT builds
  JGit v2.0.0.201206060730-rc3
  Remove Jetty p2 repository from Maven build
  Get rid of warnings about empty statments
  Removed unused parameters from private methods
  cleanup: Remove unused declarations
  Make FS OS X detection work for OpenJDK
  Use working tree iterator to compare file modes
  Further cleanup of exceptions in Git API
  Update build to use Tycho 0.15.0
  Throw formal CheckoutConflictException on hard reset
  Configure maven-source-plugin execution in parent POM
  Support gitdir: refs in BaseRepositoryBuilder.findGitDir
  Relax RevisionSyntaxException to an IllegalArgumentException

Change-Id: I05727693e0c9e762d4fc220ceadcd5a5bfb11d0d