using python2 wherever possible
Merge pull request #9 from mrshu/python2

using python2 wherever possible
central endpoint for python version detection
Suppress error output when moving videos.
Merge branch 'master' of github.com:jamalex/ka-lite
Merge pull request #10 from mrshu/python2

Central endpoint for python version detection
A number of fixes to download process, better handling flaky connections.
Fixes to subtitles: changed download domain and fixed 404 page error code.
Merge branch 'develop' of github.com:jamalex/ka-lite into develop
Revert exponents-radicals to non-empty file.

Got deleted due to no longer existing on KA site.

Need their API to match to their live data.
Video thumbnails now display for related videos on exercises.
Update to .gitignore and instruction to put independently downloaded
content in content folder.
Merge upstream