Fix the users controller routing

[netsensei]

Detailed description

The users controller uses this routing:

/user/users
/user/users/new
/user/users//show

This is confusing and complicated. The routing should be made simpler:

/user
/user/new
/user/
/user//edit
/user//delete

Context

Refactoring the routing paths, would simplify the way users are added. Make it more understandable. Also, there's this second-level "navigation" sidebar in the Users section with just one menu item "users", to get to the second level (user/users) which could be deprecated, making the interface less cluttered.