Merge pull request #13 from suxxes/master

Check if registered types extend AbstractEnumType
Remove BitDeli badge. It doesn't work anymore :(
Add reference badge
Update badges
Update composer.json
Update README.md
Update README.md
Add PHP version 5.6 to Travis config
Update .scrutinizer.yml
Update README.md
Update .travis.yml
Merge remote-tracking branch 'remotes/origin/master' into 3.0

Conflicts:
	README.md
	composer.json