Init script - change stop() function name to stop_gitlab()

On SunOS gitlab 5.11 joyent_20130814T090215Z i86pc i386 i86pc Solaris

/etc/init.d/gitlab stop fail with:

Usage: kill [-l] [-n signum] [-s signame] job ...
   Or: kill [ options ] -l [arg ...]

This is because stop function name. Changing it to something else eg. stop_gitlab fixes the problem.