fake-factory removed from requisite packages in setup.py, as it's needed only for the tests
schema_parser script now build models with RegexpValidator, when pattern is specified in json schema
RegexpValidator added to Organization model
Add on_behalf_of field to Membership.
Switch to use ForeignKey for Organization parent.
Mandate required fields of Post and Membership.

organization is required on a Post; person and organization are
required on a Membership. Use the post's organization in the
add_role and add_person functions, and remove the properties
for accessing membership_set/post_set, instead using the default
Django way of accessing.
Correct some GenericRelation help_texts.
Create Source generic relation.

If a model has two GenericRelations to the same model, there is no way
to differentiate between them. So we add a new Source model to be used
for sources.
Merge branch 'ciudadano-pr'
Merge branch 'mandate_required_fields'
tests restored after merging pull requests from mysociety
Merge branch 'make-parent-foreign-key'
conflict solved after merging mysociety/remove-dupe-relation pull request
unicode methods added to classes
Merge branch 'mysociety-add-on_behalf_of'
Don't restrict gender field to anything specific.
Fixes for Python 3.3 compatibility
Add documentation on setting up a test environment
Merge pull request #10 from mysociety/generalise-gender

Don't restrict gender field to anything specific.
Merge branch 'jpmckinney-python3'