Merge pull request #67 from ghing/49-md_use_rawresult

Unembed Office, Party
Use Document for Office, Party

Use Document for Office and Party models instead of
DynamicDocument.  As these are canonical records, they won't
have dynamic fields.

Addresses #49, #61
Fix include and exclude flags for transform.run

The #62 implementation means the registry returns lists, not
dicts.  The tasks need to accomodate this.

Addresses #49
Checkpoint commit for office lookups

Addresses #49
Don't save reporting district to RawResult.district

In Maryland, results are available at the state legislative
district reporting level.

The district from this reporting level was getting parsed out
of a value that would become the ``jurisdiction`` field and
assigned as the ``district`` field.  So, records for presidential
results or U.S. House results were getting a state legislative
district overwriting the correct district parsed elsewhere in
the loader.

This incorrect district prevented correctly looking up canonical
``Office`` records in a transform step.

Addresses #49