Feedback invitation mailer.
Make tests pass. Refactor code dealing with feedbacks.
update emails, remove session title, rename to workshop
display attendances in invitation page
update attendance confirmation email
update wording session -> workshop
remove link to session page
remove matching session title and description
in homepage
Merge pull request #77 from despo/update-emails-and-rename-session-to-workshop

Update emails and rename session to workshop
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
link to gitter
Merge pull request #79 from despo/update-invitation-text

link to gitter
Merge pull request #78 from LukasMac/student_feedback

Student feedback
spelling and punctuation
Merge pull request #81 from jlsync/master

spelling and punctuation
set_token before validation takes place and
make sure each request is only send once!