Bug 868593 - Add sinonjs support to test agent r=lightsofapollo,gaye a=npotb
(cherry picked from commit fe6828703d078db6994d98300ba82ed82497c340)
Bug 868593 - Actually add sinon r=gaye a=npotb
(cherry picked from commit db1240bab2ec2826e5b39221d700dd2145d0f529)
fixing units a=npotb