Ability to reset to remote version

[svogt]

In case of Git, this would be a hard reset to the remote branch,
in CVS / SVN one could use that to overwrite uncommited local changes

[jutzig]

Please note that this commit contains an API change and the CVS/SVN plugins need to be updated to 1.1.0-SNAPSHOT to work properly.
I should also mention that this behaves somewhat differently depending on the Team Provider.

• For Git, it reverts to HEAD in refs/remotes/origin/[branch] discarding any local commits and untracked files
• For SVN it is a local operation. All modifications are reverted and all remaining untracked files are deleted
• For CVS it's a mess that does an update -C (clean working copy)