Test CSS3 gradient generator with Jasmine

Add tests around the CSS3 gradient generator

See https://github.com/dgalarza/CSS3Factory/pull/3 for test framework set up.

CC @acostanzo 
I feel like in this case here it's clearer to see what we're testing.  The values having the prefixes is very important to this test, in fact its the core of this test so I would rather not have that abstracted out. If I was doing this a lot in other tests, then I'd probably consider it.