Add time schedule for users

[rafaelivan]

Make it possible to create a time schedule for users, registering the expected working hours.

[barbolo]

It'd be nice to have some gamification too. Each hour within the expected working hours interval that is completed makes the worker earn 1 point. Then, a ranking with all the workers from the team can be built.

[rafaelivan]

Adding gamification concepts would be of great use. In my opinion, this could be done in two steps:

1. Implement issue Add time schedule for users #19, as originally described;
2. Add gamification on another issue (not created yet).