Fix gitolite.rc config bug and add ability to manager user creation

[zstumgoren]

Two commits here:

• 351ac05 adds support for managing user/group creation, which is useful for cases (such as mine) where git user is managed outside the module (without this bit, the module errors out if git user already exists)
• b9dd428 fixes bug template('gitolite/gitolite3.rc.erb') missing, but used by gitolite::rc #14 filed by @hesco