Improve progress reporting in condensediffs.

condensediffs now shows more information on the progress of the
conversion of diffs. Along with the existing percentage, it will also
now show the number of processed items, how many there are total, and
the estimated time to completion.

Since the estimated time to completion is based on the average time
taken per item, and the number of items, the estimate becomes more
accurate over time. Instead of showing some useless numbers up-front, we
wait 30 seconds until we show the estimate. From my testing, this
appears to be a a good number, as the estimate settled around that point
in the databases I used.

This helps give administrators an idea as to how long the operation will
take, which is useful for knowing whether to keep it going or to abort
and finish later.
Merge branch 'release-2.0.x'
Fix the display of special banners, such as trophy banners.

When I moved the CSS for the special banners out of common.less, I
messed up on the rule name, resulting in the special banner CSS never
being used. This fixes the rules to use things like '.banner.yay' and
not '.banner .yay'.
Fix the last couple js-tests.

This fixes up the rest of the broken javascript unit tests. There were two
issues:

1. The way that the bug tracker links are formed has changed significantly. The
   old test was sufficient for determining that the alternate formatting
   was being used, but because of the new redirect URLs, the contents of the
   comparison had to change.
2. The signature of the 'destroy' signal had changed, and the comparison was
   no longer succeeding.

Testing done: Ran js-tests in firefox.

Reviewed at https://reviews.reviewboard.org/r/6232/