omego migration

This rather large PR refactors the `OMERO-qa-upgrade.py` command in order to allow a wider variety of uses across the team. This first required extracting and slightly modifying the http://github.com/openmicroscopy/snoopycrimecop plugin infrastructure, which could later be further abstracted to its own project. CLI and ENV processing was all converted to use argparse, and packaging was added to support pypi/pip installation.

To test create a fresh virtualenv (adding `argparse` if Python 2.6 or lower) and run:
```
pip install git+ssh://git@github.com/joshmoore/omero-setup.git@omego-migration
```

The only available command at the moment is `upgrade`:
 * `omego upgrade -h` will list options
 * `omego upgrade -v -n` will list options with values
 * `omego upgrade` will perform a default installation of OMERO.

One of the first tasks will be to separate out `init` logic from `upgrade` so that it's clear whether the user was intending to upgrade an existing server or create a new location. Various other tasks are then planned: recording all installed servers (e.g. under `~/.omego`), allowing data bootstrapping, etc.

/cc @ximenesuk @sbesson @manics @jburel @Criswell @knabar @stick

See: https://trac.openmicroscopy.org.uk/ome/ticket/11339#comment:4