Merge pull request #18 from daanvc/master

implemented answer service
Fixed the answer states so they make sense
Merge pull request #20 from teugis/master

Fixed the answer states so they make sense
Added missing method in IFeedbackService

Fixed typo in IReviewService
Added missing method in IFeedbackService
Fixed errors du to missig Answer states.
Merged Main repo in my fork.
Merge pull request #21 from teugis/master

Added missing method in IFeedbackService
Fixed typo
Merge pull request #22 from teugis/master

Fixed typo