Add hook to stop merge commits into the master repository

[Amar Takhar]

A developer had an issue where they accidentally pushed local code that generated a 'merge commit'.

It's been suggested a hook be added to the server side repository to stop this from happening.

Here is one such hook I'll have to test it out before adding it:

​https://stackoverflow.com/questions/2039773/have-remote-git-repository-refuse-merge-commits-on-push

I will also add:

[receive]
    denyNonFastForwards = true
    denyDeletes = true

To the main repo to block any accidental --force pushes. If we are blocking merge commits it makes sense to block this as well.

[Chris Johns]

Sounds great, many thanks.

[Amar Takhar]

This is an option in Gitlab.