adds uniqueness to enrollment
Merge branch 'master' into enrollments

Conflicts:
	db/schema.rb
Merge with master
Wrote test for enrollment duplication and added reenrollment function
Added check for user in enrollment spec
Merge pull request #99 from boersmamarcel/enrollments

adds uniqueness to enrollment
Cleaned up ChallengesController
Update README.md

Coverage!
Added Coveralls
Merge branch 'master' of https://github.com/boersmamarcel/challengesplatform
Removed brakeman
Updated travis.ytml
Fix for travis
travis fixje
Fix for user
Update rakefile
Merge pull request #106 from boersmamarcel/refactor_challenges

Cleaned up ChallengesController
removed travis-pro attribute
Merge branch 'master' of https://github.com/boersmamarcel/challengesplatform
Update README.md