Slight tweak to docker dev files

Use -p 8000:8000 instead of -p 8000.  This works better with older
docker versions.  Also we can remove that extra flag from the
runserver command.
Fix add subtitles link (#1349)

This was failing because the widget code is compiled with the closure
compiler, but the other code isn't.  Closure munges the variable names
to optimize them which was causing the issue.  The workaround hack is
to use script notation to access the variables.