Add running a charity specialist sector

Part of https://www.pivotaltracker.com/story/show/67287568
Counterpart to https://github.com/alphagov/panopticon/pull/148
Merge pull request #549 from alphagov/add-running-a-charity-specialist-sector

Add running a charity specialist sector
Add Competition SpecialistSector

Part of https://www.pivotaltracker.com/story/show/67991848 and counterpart
to https://github.com/alphagov/panopticon/pull/147