Fix retina icons
[Bug 887017] Add GA tracking to related links.
[Bug 867221] Show hot questions on product pages.
[bug 892610] Patch TestWikiVideo with mediocrity

This changes the test so it accepts the previous output I was getting
and the new output I'm getting now. I suspect the difference in my
system is that I updated from libxml2 2.8 to 2.9.1 and in doing that
I get slightly different output.

This is goofy, but I think both outputs are "good enough" and I think
Ricky said the video stuff in the wiki isn't long for this world anyhow.
Fix bug number transposition typo
[bug 741789] Stop using fixtures in access tests.
Update patching docs to what we actually do
Tweak docs to cover collectstatic/compress_assets

Before running the LiveServerTestCase-based tests, we need to run:

    ./manage.py collectstatic
    ./manage.py compress_assets

This change attempts to clarify that in the test docs.
[bug 889833] Fix excerpts for contributor forum searches

This re-adds excerpts for contributor forum searches.

Further, it fixes a bug where we were setting number_of_fragments to 0
which causes ES to highlight the entire content and ignore fragment_size.
If we set it to 1, then it picks one fragment and limits it to the
fragment_size.

That might cause other issues, but it's the right thing to do otherwise
excerpts can get huge especially for support and contributor forum results.
[bug 890268] Remove old topics from templates