Handle missing initial OMERO-CURRENT

On a first installation, mklink is now called to point
OMERO-CURRENT (i.e. self.sym) at the self.dir location.
This satisfies all the requirements for lib/python etc
even though it is a bit counterintuitive.
Remove odd _() syntax

Though it was an interesting way to try to reduce
character counts in the original OMERO-qa-upgrade.py
the passing of `_` as a variable is confusing to
say the least. Now using a simple `def run` method.
Add TODO for windows delete
PyLint cleanup including args refactoring

Remove unused imports and fix all error messages
from PyLint/PyFlakes. Rather than passing around
the individual arguments, now passing the single
`args` namespace.
pep8 compliance as imposed by flakes8
More fixes from the args refactoring