[GCI Task] Currency Integration Test Suite

Sorry for getting this through late. Some things came up.

Done for [this Google Code-in task](https://www.google-melange.com/gci/task/view/google/gci2014/5338390308323328) which includes to [this task](https://www.google-melange.com/gci/task/view/google/gci2014/6386606604812288) and [this task](https://www.google-melange.com/gci/task/view/google/gci2014/6413395121143808).
Use proper generic