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.