Changed to Thin webserver for development (hides WARN Could not determine content-length of response body.)
Wrote specs for user and challenge
Fixed can_unenroll
Merge pull request #185 from boersmamarcel/upcoverage

Improved coverage for user and challenge spec
Merge branch 'master' of https://github.com/boersmamarcel/challengesplatform into declinedoverview
Fixed overlap in challenges and removed unenrolled challenges from dashboard
Update look and feel of challenges