Some tweaks :
- Optimized the hour validation regex
- Added default desciption for activities with no description
- 23:58 + 10 min gives 00:08 instead of 24:08
- New days start at 8am instead of 5 :p
- Style tweaks (no outlines for the inputs)
- Added visual aid for validation when clicking on ok with incorrect data (on top of the live validation)