Add models for representating relationships between organisations

We need this for representing the link between constituency
offices and parties, but it would also have been useful for
representing party -> coalition relationships around the
Kenyan election.
WiP
fixup! Add models for representating relationships between organisations
WiP
Increase the max length of the Place slug to 200

This makes it consistent with the lengths of the other slugs
in the models file and allows us to store some consituency office
place slugs that end up longer than the previous max length (100).
Don't include party twice in organisation names
Fix whitespace and indentation
Fix a typo - need the area, not the code
Actually create places
Remove a duplication of the Organisation on a Place page
Also create contact details for each constituency office
Actually create constituency contact positions
WiP
Switch zimbabwe to using the Twitter Javascript widget too
WiP
Merge branch 'constituency-office-wip' into south-africa