Add a Manager to the election model
Add a Manager to the election model

with methods to handle the various things that are currently done in
setting.py by processing the elections settings.

DemocracyClub/yournextrepresentative,datamade/yournextmp-popit,mysociety/yournextmp-popit,neavouli/yournextrepresentative,neavouli/yournextrepresentative,mysociety/yournextmp-popit,mysociety/yournextrepresentative,mysociety/yournextrepresentative,datamade/yournextmp-popit,datamade/yournextmp-popit,datamade/yournextmp-popit,mysociety/yournextmp-popit,mysociety/yournextmp-popit,datamade/yournextmp-popit,neavouli/yournextrepresentative,DemocracyClub/yournextrepresentative,neavouli/yournextrepresentative,neavouli/yournextrepresentative,mysociety/yournextmp-popit,mysociety/yournextrepresentative,DemocracyClub/yournextrepresentative,mysociety/yournextrepresentative,mysociety/yournextrepresentative