This is an old script I've created to create a signature file for all of your Google Apps users, then push that generated script to their Google profile to make signature management loads easier since Google Apps doesn't give you that option. I hope this helps anyone out there having the same issues I was having finding a free solution to this problem.
All you'll need to do is download and install GAM: https://github.com/jay0lee/GAM
Get your Google Apps key setup with GAM, then modify gamplay.py with the location of your GAM file, and you should be good to go!
Written with Python 2.7 in mind, the last time I used this (awhile ago) it worked just fine so let me know if it's buggy for you.