Eliminating superfluous header files in unit tests

These header files used to be a lot more extensive, but now all contain empty or nearly-empty class definitions.  Those tests which still require extensive setup have been left with their original headers, but all others which are merely class declarations have been integrated with their respective source files.
Merge pull request #26 from leapmotion/ref-testheaders

Eliminating superfluous header files in unit tests