Added option to allow untracked files as non dirty

In this commit, the option only works for git but it should not be to hard for
someone who knows svn to so the same.
This commit is largely inspired by @yoavweiss, I only added an option to use
it.
mvn plugin was missing "redeploy" completion for tomcat.
Merge pull request #1747 from dhemmerling/mvn_tomcat-redeploy

mvn plugin was missing "redeploy" completion for tomcat.
Merge pull request #1745 from jtheoof/master

Added option to allow untracked files as non dirty
Merge branch 'master' of git://github.com/robbyrussell/oh-my-zsh
Merge upstream into local master.