Add endpoint listing all the locations as well as the location view
Allows moving a meeting from a calendar to another one

This is only possible when editing a meeting of course
Sometime the input submitted in the form is a time object form the start
Adjust the add_meeting method to the changes made in the form
Use choices=[] to make things simpler (since it works)
Merge pull request #74 from fedora-infra/move_meetings

Move meetings