Get multiple srts to work by exposing srts at a URL, then having the video template use them.
Merge branch 'release-0.11' into multiple_srts
Fixing bug--sometimes context processors CAN be called before middleware!
Merge branch 'refactor_main' of github.com:bcipolli/ka-lite into multiple_srts

Conflicts:
	kalite/i18n/custom_context_processors.py
Fixing up more broken tests.
only add subtitles if they exist on disk.
Merge pull request #1021 from bcipolli/multiple_srts

Multiple subtitles support