Add container listing helper

This might be useful if we want to let the user select the container
to show.
Remove duplicated removeClass call
Animate loading text

Instead of a static background image, the text "Loading..." is now
displayed while the title and thumbnail is loaded. The "..." is
animated. When the thumbnail is loaded, the text faded away.
Show object count in header
Remove funny colors depending on who updated what
Show events in a log file at the bottom of the screen
Smaller log over AJAX requests
Fix width of bottom ajax log

Before, the right side gap would vary in size since it was 5% of the
browser width. It is now fixed at 10px, like the left side.
Darken background and adjust ajax log to match
Play video when clicking thumbnail

This unfortunately hard-coded the video type to video/mp4 and the
uploaded videos must now match this type. Transcoding the video to a
type understood by the browser is left as an exercise for later...
Make ajax log keep position when scrolling