Updated scanEIT.py so that it accounts for both circular polarizations.

Also refactored the script slightly so it can be invoked directly without a call to python.
Also also added command-line option to specify output plot filename.

Result is essentially 2x the previous, but it is more complete. This finishes all the issues I've found, so I'm at a loss for what else could be wrong that is causing so much trouble.
![test](https://cloud.githubusercontent.com/assets/6655329/5283004/d6cfab06-7ad8-11e4-99b2-051491a6b1b2.png)