Pome JS tests now part of build

Moved rdf/src to rdf/rdf_common_jvm/src so that IDE's work nicer. Otherwise, I have just got pome compiling OK and the tests pass.

I have also used my plugin https://github.com/InTheNow/sbt-scalajs that allows scalajs to test and compile as per a scala project - i,e

sbt test
Why not try to have them work together, and if we have a problem that is indeed serious we can split. Here we are trying to get to the point that there is the least duplication possible. This does not slow down the main projects which are understood to be RDF, Sesame, Jena and Plantain. In fact we are just laying the groundwork here to get Pome back into plantain, and to remove the duplication of tests for pome and rdfstorew.