Fix source fields in RiaH mapping view

[janblom]

Underlying problem was that the class MappingPanel handles both table -> table and field -> field mappings, since they are higly similar. Recently some functionality was added that should only apply to tables (hiding tables from the view), but it affected the field -> field views as well.
This was fixed by making the MappingPanel class aware of the type of mapping it was handling (between tables or between fields).
A test was added to confirm this. Since the RiaH tests take a significant amount of time, the tests were moved to the verification phase (use mvn verify to run them).

[Spayralbe]

Haven't reviewed the code changes yet, but one thing I noticed when using the app is that the source fields are now indeed visible (as expected) when entering a field to field mapping view, but they are still hidden when exporting the specifications as mapping docs (any format).