Replace occurrences of `https://github.com/jamalex/*` with `https://github.com/learningequality/*` in some documentation.
Removed extra `)` character at `scripts/cronstart.bat` which may prevent the script to continue running cron jobs in Windows.
- Add missing image file on `static` folder which is referenced by `INSTALL.md`
- Update `INSTALL.md` with some fixes to point repo from `https://github.com/jamalex/` to `https://github.com//learningequality/`.  Also update the Python and Git urls and download locations.
Bug fix for python on `counter` "defined before use" exception.
Allow starting `cronstart.bat` with number of seconds for `cronserve` as argument.
Allow starting `cronstart.sh` with number of seconds for `cronserve` as argument.
Allow starting `start.command` with number of seconds for `cronserve` as argument.
Merge pull request #2049 from cpauya/hotfix/2001-cron-on-windows

Hotfix/2001 cron on windows
Merge branch 'release-0.12.0' of github.com:learningequality/ka-lite into fix_set_server_language

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