Flake8 omero/util

This PR fixes the flake8 warnings from `omero/util`

One external file has been moved untouched to `omero_ext`. Three files have been removed, these are all: unimported by anything and: have no main method, are clearly old or are clearly broken.

Travis and Jenkins should both pass.


Hmmm.....odd. Not sure what @cneves was up to. Guess let's assume the doc comment was correct.