Refactor parser and metadata test cases

We need to refactor the parser test cases to separate example parsing verification (we should always be sure that our samples is correctly parsed) and pure unit tests verifying particular behavior and error in parsing and/or construction of metadata.
We need also to have a way to better maintain example parsing tests (idea: use junit Theory)
It affects all metadata parser (standard, -ra.xml, -ds.xml, -ironjacamar's)