Squash migrations for v1.0

[mikkonie]

Suggested by @holtgrewe, seems like a good idea. Especially projectroles has accumulated a lot of migrations as of late.

Provided there are no unforeseen problems, let's go with it for the v1.0 release.

Should of course be done as close to release as possible, maybe even after #1389.

Django migration squashing docs

Tasks

• [x] projectroles
• [x] adminalerts
• [x] bgjobs
• [x] filesfolders
• [x] sodarcache
• [x] timeline
• [x] Fix AppSetting unique_together setup in squashed migration
• [x] Reformat projectroles and timeline migrations

[mikkonie]

Done.