[requirement][all] Nose being removed from Debian and Ubuntu: let's remove it from our global requirements

Hi, It's no surprise for anyone that's been following it: Nose was deprecated years ago, and now, we're trying to remove it from Debian. Therefore, 49 bugs were filled against the Debian OpenStack package. It'd be nice if upstream OpenStack was also following this move, and removing nose from global-requirements. I'm not sure if it'd be a big deal if that wasn't the case, as I could use a different test runner in Debian, but I very much would prefer if it was the case. Probably Ubuntu will follow the same path, since Nose isn't in main (it's in Universe, meaning Debian maintained...). Your thoughts? Cheers, Thomas Goirand (zigo)