Add git hook to run nosetests on non-master branches

[cpcloud]

Not sure if this warrants an issue but it might be useful to do this across the board to prevent regression.

[btel]

I usually run nosetests from the current branch I am working on (usually dev). Isn't it enough?

[cpcloud]

I was thinking that when one tries to commit, a git hook could run nosetests and won't allow a commit until all tests pass. This probably doesn't warrant an issue since I could do this just for my version of the repository without forcing everyone to adopt this convention.