Merge: Test out-of-tree projects

Merge: Test out-of-tree projects

This is a simple script that allows jenkins (and human users) to test out-of-tree projects that live in other repositories.

The main file is `contrib/oot.txt` that contains the various projects and `contrib/oot.sh` that tries to build them.

A preview of the current state is available at:
http://gresil.org/jenkins/job/nit_oot/lastCompletedBuild/testReport/

I will improve the script to add checks.

Pull-Request: #2379
Reviewed-by: Alexandre Terrasa <alexandre@moz-code.org>