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 believe so, `decimal.toString(16)` returns the hex value and just leaves out the prefixing 0 when there is none which hex colors require. Are you thinking theres something else?