Move the 2013 Kenyan election data into the kenya subdirectory
Add external_id columns for Place, Position and Organisation

This is for issue #558 - for Kenya we would like to keep the
IEBC API in the database as well, to make it easier to update
from the API in future.
Store the cached API data from 2013-02-08 in the repository

It's debatable whether this kind of data should be in the repository,
but at the moment it's a big help if it is.
Update paths to the data directory and API cache
Add an option to get_data_with_cache to force only using cached data

It's sometimes useful to make sure that we're only using cached
data, to make sure that we're using a consistent set rather than
mixing new API data with old.
Add a command to set IEBC APIs in external_id for aspirants, parties and places

This should really have been done at the time of import, but this
script uses the same loop and the same data to do the same
after the fact.