Review of README and bug fixies
1) EXTEND readme with functionality
- ADD screenshot link
- ADD Future section
- EDIT Thanks section
2) FIX broken regular training lesson redirect after destroy
3) FIX colorize_negati_positive helper
- missing BigDecimal check
4) EDIT permissions
- separate watcher permission
- small fixes
5) FIX training lesson realization has_coach?
- broken logic resulted into broken action buttons shown
6) ADD doc folder
- ADD sample screenshots