Fix celery issues

See merge request funkwhale/funkwhale!563

Fix #684: Include shared/public playlists in Subsonic API responses

See merge request funkwhale/funkwhale!561

Fix #670: Use proper locale for date-related/duration strings

See merge request funkwhale/funkwhale!560

Fix #683: wrong number of affected elements in bulk action modal

See merge request funkwhale/funkwhale!559

Resolve "Error 500 when loading /api/admin/music/track/99104/change/ (edit track  via django admin)"

See merge request funkwhale/funkwhale!556

Test install docs for 0.18

See merge request funkwhale/funkwhale!551

Translations integration

See merge request funkwhale/funkwhale!550

Fix #663: Do not try to create unaccent extension if it's already present

Closes #663

See merge request funkwhale/funkwhale!549

Lots of small fixes in the documentation

See merge request funkwhale/funkwhale!548

fixed broken build

See merge request funkwhale/funkwhale!547

Based Docker image on alpine to have a smaller (and faster to build) image

See merge request funkwhale/funkwhale!546

Nodeinfo improvements

See merge request funkwhale/funkwhale!545