Add motion validator

Validate motions files (and fix motion_id → id)
Rebuild parties

Change to party names, rather than groups. Split Liberal People’s Party
from Liberals.
Cope with old id for /kd party

Used to go by ‘skl’. We should really have a way to store things like
this in the data. #16
Converted vote data

Data files of vote data, converted from KM format to Popolo.