Interface methods in the vtable are called on current class, not interface.

During optimization Dalvik checks if method is invoked on an interface, which causes warnings or errors. To prevent this, we assume that the class we are generating vtable for implements the interface, invoke the interface method on that class and let Dalvik resolve it at runtime.
Merge pull request #15 from izzytwosheds/bugfixes

Interface methods in the vtable are called on current class, not interface