Fix #1214: Django uses lcased language tags to set language, with dash--not ietf format, not their directory format.  So, have different conversion functions for each Django format.
Fix #1215: move subtitles from locale folder into static/subtitles
Give more room for the language name in the interface, and a bit of linting
Fix #1208: include querystring when redirecting after setting language.
Fix #1186: Must convert unicode strings to string using the unicode function (not str)
Avoid any future issue similar to #1186: Must convert unicode strings to string using the unicode function (not str)
Merge branch 'release-0.11.1' of github.com:learningequality/ka-lite into bugbash_fixes_1

Conflicts:
	kalite/updates/views.py
Merge pull request #1218 from bcipolli/bugbash_fixes_1

Bugbash fixes 1: #1186 #1208 #1214 #1215 - an i18n slugfest :D