Also fix a case where offline_since can be nil.

fixes #6220

closes #7120

closes #7119

closes #7089

closes #7066

Turns out that postgres can't handle "0" as boolean, but mysql can
handle "false".

closes #7115#pullrequestreview-699342

closes #7096

closes #7071

Also fixed the "fix public photos"-migration, because it didn't work
with migration-models :/

fixes #6177

Turns out there is a difference between hg and git and I should not
switch that often.

closes #7109

closes #7102

closes #7100

closes #7107

closes #7105

Signed-off-by: Lukas Matt <lukas@zauberstuhl.de>

closes #7095

closes #7094

fixes #7093

closes #7092

closes #7091

This reverts commit 5fcc239d.

closes #7082

closes #7070

closes #7076

closes #7088

Some pages need jquery in the head and instead of loading it twice on
these pages, it is better and easier to load it in the head on all
pages. It should be in the cache after the first load anyway.

closes #7086

closes #7085