First pass at office and party fixtures

Currently these only have:

* Offices for MD
* Democratic and Republican Party

Note that I used "Superintendent of Schools" as the office name,
even though there doesn't seem to be a decision made here yet
according to
https://github.com/openelections/specs/wiki/Office-Names

Addresses #61
Convert party.csv to ASCII

Somehow it got saved to UTF-16 and mongoimport choked on it.

Addresses #61
Invoke task to load party and office metadata into Mongo

The invoke tasks calls through to ``mongoimport`` for the heavy
lifting.

Addresses #61
Clean up office and party fixtures

* s/Democratic/Democrat/
* s/House/U. S. House/
* s/Senate/U. S. Senate/
* s/State Upper Chamber/State Senate/
* s/State Lower Chamber/House of Delegates/
* Add ``chamber`` field

Addresses #61
Merge pull request #64 from ghing/61-populate_office_party

Fixtures and invoke tasks for loading office and party metadata