Bug 29002: Enable editing bookings from the timeline

Bug 29002: Enable editing bookings from the timeline

This patch allows for editing bookings using drag and drop on the
timeline view.

Test plan
1) Follow the test plans from the previous patches
2) Navigate to the bookings tab of a biblio where you have created some
   test bookings
3) Note you can click on a booking in the timeline to highlight it.
4) Note you can then drag the booking forward or backwards along the
   timeline to trigger an edit
5) Note you can drag the start or end of a booking to extend a booking
   and trigger an edit

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Janet McGowan <janet.mcgowan@ptfs-europe.com>
Signed-off-by: Caroline Cyr La Rose <caroline.cyr-la-rose@inlibro.com>
Signed-off-by: Laurence Rault <laurence.rault@biblibre.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>