Add text about mailing the paparazcie for a full resolution photo

Closes #530

See merge request !686

Update requirements and fix icon generation in fixtures

See merge request !688

They're generated as PNG, but the model doesn't like that very much.
Somehow the form fields handle this correctly though. I suspect content
type isn't passed around correctly.

Release script to facilitate the release procedure

See merge request !685

Lower case username in token API

Closes #561

See merge request !678

Update texts to new location board room

Closes #563

See merge request !683

Removed usage of old is_active method in newsletters app

Closes #562

See merge request !681

Show cancellation dates in event admin

Closes #499

See merge request !659

Updated book list for the second semester

See merge request !677

Clean up registrations code smell

See merge request !675

Send website emails not from info@thalia.nu

See merge request !676

Send them from noreply@thalia.nu instead, as the site isn't allowed to send from info@

Testing this makes no sense, as it's a setting.

Fix wikilogin

See merge request !673

Remove python35-django11 testing on CI

See merge request !672

Use docker container from own namespace

See merge request !670

Fix event pages when user is not logged in

See merge request !666

Remove old prefetches from the mailinglists

See merge request !664

Really fix photos pagination this time

See merge request !663

Fix photos index view if more than 7 pages exist

See merge request !661

Add constraints to the members app

See merge request !658

Make partner optional for PartnerEvents

Closes #542

See merge request !653

Correct usage of django.utils.http.urlquote

See merge request !652