Merge pull request #1 from rsinnet/master

Adding bash completion for submodule-ext.
git-submodule-ext: Changed 'refresh' to use explicit -b, --branch option
git-new-workdir, git-submodule-ext: Adding libexec path for maximum flexibility
git-submodule-ext: Changed --include-staged to --cached
git-submodule-ext: Split up help commands
git-submodule-ext: Fixed set-url with recent --cached flag change
Updating Bash completion.