Add one test
Adds
Adds challenge model test
Fixes coverage to 100% for challenge model
Adds coverage for user
Fixes coverage for challenge decorator
Fixes days count
Fixes days count
Hide nonapproved challenges from landing
Able to send a message to supervisors
Merged
Merge pull request #221 from boersmamarcel/coverage

Coverage
Add one test
Adds
Adds challenge model test
Fixes coverage to 100% for challenge model
Adds coverage for user
Adds messages for challenge unenroll, decline and approve
Fixes coverage for challenge decorator
Fixes days count