Update bitbucket URL for latest bitbucket behavior

URL was /changeset/sha1 and is now /commits/sha1
Merge pull request #206 from MarkEWaite/master-update-bitbucket-url-base

Update bitbucket URL for latest bitbucket behavior
Fixed help and added docu for namespaced branches

See git-client-plugin Pull Request
https://github.com/jenkinsci/git-client-plugin/pull/120
[FIXED JENKINS-19001] extension can declare requirement for a workspace during polling
[maven-release-plugin] prepare release git-2.0.4
[maven-release-plugin] prepare for next development iteration
Reverted wrong change regarding "any branch"
Switched to new git-client 1.6.4 containing namespace fix
Merge pull request #207 from alexanderlink/namespace-branch-help

Fixed help and added docu for namespaced branches
Merge remote-tracking branch 'upstream/master' into proto-additional-logging-in-GitSCM

Conflicts:
	src/main/java/hudson/plugins/git/GitSCM.java