Remove users STI
CanCan authorization
One user can manage multiple departments.

Rename 'dept_head' to 'department' in URLs. Store current_department.id in URL.
Single menu for single user

Redesign it using guest part menu
Admin part enhancements
Throw away useless code.

Displaying of 'alien' specialities in department's specialities list doesn't working anymore
Merge branch 'auth'
App layout little fixes, using page title on most pages