PopIt mirroring: add an option for not inlining memberships
PopIt mirroring: split commands to dump Popolo JSON / send to PopIt API

After the earlier refactoring there's a lot of common code involved
in dumping data in Popolo JSON format (suitable for directly importing
into mongodb for example) and sending them to a PopIt instance using
PopIt's API - this code is now moved to pombola/core/popolo.py, and
used by both core_send_people_to_popit and core_export_to_popolo_json.

This commit also includes some minor tidying-up of the code.
Fix the syntax for catching multiple exceptions

Previously, this would only catch ImportError exceptions, due
to the way the amiguity described here:

  http://legacy.python.org/dev/peps/pep-3110/#rationale

... is resolved.
PopIt mirroring: add hooks to add country-specific data for PopIt
PopIt mirroring: for South Africa add URLs for people & organisations
ZA: Add members interests data to PopIt export

(Minor refactoring by Mark Longair.)
ZA-specific fields for PopIt export

Adds lat and lng fields to constituency office exports.