Prepare for 1.1.0

This consists of the larger portion of improvements that will result in shifter 1.1.0

The following news has been added:

• Automated Shift Exchange mechanism + logs. closes #29
• Notification system
  • for new plans with shifts,
  • for shift exchanges, closes #18
  • for studies (selected states: Planned/Booked) closes #19
• [bugfixes] Related to links, shift displays, and selected forms in the service. closes #44

All these are available on the test server: https://shifter-lab-01.cslab.esss.lu.se/

Please test/approve. I want to keep it open until all identified bugs and requesters are fixed