This implements a proper --mirror option when mirroring.

Adding ability to mirror tags in svn repository

If run in a cron job and gitlab is off-line update_mirror.sh
would turn the SVN repository into a bare repository.  This
then breaks the SVN mirror until bare is set back to false.

add_mirror.sh script will now add a git mirror to gitlab!

update_mirror.sh will now update mirrors that have been
added to gitlab!