Create abstract TestBfMatlab class to manage the java class path

- Clean the java class path at the beginning and end of each test
- Clean up TestBfGetPlane to use directly FakeReader
- Derive all unit test cases from TestBfMatlab
Reader default X and Y sizes from FakeReader to perform tile tests
Merge pull request #547 from sbesson/rebased/develop/matlab_unittest_cleanup

Matlab unit tests cleanup (rebased onto develop)