Project list widget throws an internal server error

[KasperBrandt]

Test plan

GIVEN the 'Grab a widget' page

WHEN a project has no partners
THEN the project list and project map options should not be available

WHEN a project has partners
THEN all widgets should be available and not display an error

Issue description

The project list widget gives an internal server error. And the map widget as well: http://sentry.support.akvo-ops.org/rsr/live/group/727/. This is due to the fact that they don't have a reporting organisation and the map and project listing widgets expect an organisation as an input.

The reporting organisation here should be changed to the project's primary organisation, and we should create a 404 exception when the project has no partners at all, just in case.