371 timeslots

Fixes #371 . 
In short, this PR recovers all Timeslot-related functionalities of the broken tooltip.js and they are now realized in non-ajax, full-page-reload forms.

With this PR time_slots can now be created/edited and deleted from links in the view. 
Repeating time_slots can also be created/destroyed accordingly with all the different options.

We should fix recurring shifts as well and then according to @caseywatts, devs would then be able to upgrade to Shifts 3!