So I found a solution that works for me.
As far as the pre-push hook goes, it actually does exist. (This is just to answer the comment VonC left).
As of git 1.8.2 the pre-push hook can be run. So, what I am doing is exiting with a non zero value from the pre-push hook when I try to push and a certain file I specified in the pre-push hook contains a certain string.
So I guess that does what I needed to do. I can see that doing this on the server side is better, but in this situation I needed it to work this way.
So, by using git 1.8.2 it can be easily accomplished by using the pre-push hook.