Round totals instead of ceiling in detailed reports
Fix JSON serialization error
Fix copy-paste error in datetime converting

We use naive datetime for daily reports only because we need timestamp
values in UTC there.
Revert "Fix copy-paste error in datetime converting"

This reverts commit df25029cf7a5599a5219ebda7f715ac556e74b71.
Admin reports: get_summary() processes naive datetimes
Admin reports: remove silent try-except

We skipped an error if `pytz` module was inslalled.
Add `css_overrides` block that will go below the `css` one

This way it will always override any Pootle default styles on any pages.
Make HR lines semitransparent so that they work against any colored background
Improve thumbnail styling in normal/hover/focused states
Make browser actions hidden by default to avoid flicker on data load
Prevent crazy collapsing/expanding of stats drawer when stats data is refreshed

Also, expand or collapse only the first time; if user prefers to have the stats collapsed,
leave it intact on stats reload.
Cleanup: s/mimetype/content_type/

The `mimetype` argument to `HttpResponse` is deprecated and will be
removed in Django 1.7.
Requirements: drop memcached in favor of Redis

Refs. #3351.
Address code arrangement/styling issues raised by Julen
Settings: Add logging settings to 20-backends.conf