Use git client plugin 3.0.0-beta7
Use git client plugin 3.0.0-beta7

Includes automated test fixes for CentOS 6.

v1v/git-plugin,martinda/git-plugin,MarkEWaite/git-plugin,martinda/git-plugin,martinda/git-plugin,MarkEWaite/git-plugin,jenkinsci/git-plugin,jenkinsci/git-plugin,v1v/git-plugin,jenkinsci/git-plugin,MarkEWaite/git-plugin,v1v/git-plugin,jenkinsci/git-plugin,MarkEWaite/git-plugin