Added support for bind_hostname options.

See also related wptserve PR https://github.com/w3c/wptserve/pull/10
Match new args to start_http_server() to wptserve.
Un-global bind_hostname & pass it properly instead
additional mathml tests as requested by Denis Ah-Kang
clean up tests after initial review
multiple asserts in one test
path to test harness
Don't pass pywebsocket -H if bind_hostname != true
merge multiple asserts into tests after review
Merge pull request #740 from davidcarlisle/davidcarlisle/math-parse03

additional mathml tests as requested by Denis Ah-Kang
Simplify a bit (in response to jgraham review).
Fixed variable name.
Merge pull request #726 from w3c/submission/sideshowbarker/bind_hostname

Added support for bind_hostname options.
Updated to latest upstream wptserve.
Move the WebVTT white.mp4/white.webm support files to /media

It would be nice to use these in other media tests as well, since they
are white and silent, whereas movie_5.* is red and clicks.
Merge pull request #757 from foolip/mv-white

Move the WebVTT white.mp4/white.webm support files to /media
Update manifest iterator to be more useful
Merge pull request #762 from w3c/jgraham/manifest_iter

Update manifest iterator to be more useful