Feedback invitation mailer.
Make tests pass. Refactor code dealing with feedbacks.
Merge branch 'master' of https://github.com/codebar/planner into student_feedback
Refactor. Add aditional test. Make feedback rake task more informative.
Adjust feedback rating validation message
Improove feedback request email text
Improve Feedback request mailer spec
Merge pull request #78 from LukasMac/student_feedback

Student feedback