Tests failing occasionally about braintree-node

[sobafuchs]

Thanks, it's an issue with the timeout - mocha defaults to a timeout of 2000ms. Problem is, the time it takes to hit braintree's servers and come back probably exceeds that. I'll probably need to stub out the braintree functions, but the functionality should still work (I use the library at my company).

[sobafuchs]

Also @michaltakac appreciate the help. Haven't really used subscriptions yet, so any help on that front would be a huge assistance

[michaltakac]

I've been wrapping my gateway.subscription.* methods in Promises so considered it would be helpful to add them to this package and then use it in my projects, others would also benefit from it I guess :)

[sobafuchs]

Sorry about letting this repo go. I'll try to stub out some of these braintree methods so the tests dont timeout occasionally + I'll try to maintain this better.