Fix age display: use a blocktrans instead of {% trans 'ago' %}

In some languages, like french "ago" is a preposition, so doing
something like "{{ value }} {% trans 'ago' %}" will not work, we have to
use a blocktrans.
Properly escape comments in comment_filter template tag.
Bump grappelli/filebrowser versions.
Version bump to 1.4.6
Added tag 1.4.6 for changeset 94f1427035e1
Update auto generated CHANGELOG, requirements, settings docs.
mezzanine.accounts czech translation update
Apply URL processing lazily, so translation proxies are only evaluated after language is determined.
Merge branch 'feature/translatable-accounts-urls' into develop
The LocaleURLMiddleware now stores current language in session on each request.
This is done to prevent language switches on redirects (such as the login redirect) which in most cases don't use a language prefix.
Merge branch 'feature/language-chooser' into develop
Merge branch 'master' into develop
Bump update times -- the "ago" trans to blocktrans change doesn't seem to require an actual update.
Merge branch 'feature/polish-translation-update' into develop