Added a webservice function for the description extractor.

rpc.py:
- Added the function descriptionExtract().
- Standardised indentation.

models.py:
- Added a RawVar and an Allele class for the webservices.

describe.py:
- Made the RawVar class a child of models.RawVar. This is convenient for
  webservices since we can simply return this object.



git-svn-id: https://humgenprojects.lumc.nl/svn/mutalyzer/trunk@591 eb6bd6ab-9ccd-42b9-aceb-e2899b4a52f1