Merge Invites branch and resolve conflicts

* Batch invites
* CSV invites import
* More controls on the students invites
  * Force resend invite
  * Send pending invites only
* Add sent field to StudentInvite

* Authorization for students to fill form
* Fix typeahead for new elements
* Few minor view fixes to support student authorization
* Invite codes are now reset once the form is filled

Fix send JSON for recipient vars
Hide project title if work place type is job
Site options
Use email text from db; Create site option