Changes to the log system

- View Event history now shows the logo of the org whose action triggered the log entry
- View Event History now shows different fields than before
- Proposals now logged
- Accepting / Discarding a proposal now doesn't create junk edit / delete entries as before.
- Creators of an event can now see all of the log entries altering an event in the event history log. This includes deleted events.
Changes to the logging and scheduling

- Scheduled tasks for pull / push now working as intended
- Rescheduling of all tasks fixed
- protection against the rescheduled task ending up in the past

- further event history fixes
- fixed lots of erroneous logging
- performance improvement with logging (no longer loading controllers for no reason)
- logging extra actions that weren't logged before (proposal accept / discard, server pull / push)