fix(tests): Update service-mixin tests.

![image](https://cloud.githubusercontent.com/assets/128755/3883293/c7035a02-219f-11e4-97df-d034e043b838.png)

If you're putting these on the mixin object, do we need to do this `<privateMethod>.call(self,..)` pattern anymore? Can we just do `this.<privateMethod>`?