1. New API error format introduced
2. CamelCase was removed from API (evaluations and participants)
More improvements to evaluation API
1. Stub for a person's photo was added
2. More improvements to Evaluation, Participants and People API
Small fixes after code review
Merge branch 'improved-eval-participants-api'

Conflicts:
	app/controllers/Participants.scala
	app/utils/EnumUtils.scala