User management
1) ADD curriervawe for image upload
- user avatar
2) EDIT UsersController
2.1) index - onbtain users in depence of roles
2.2) create - generate passwd + send email
2.3) FIX update
3) FIX user information in template
- in the header + in the sidebar
4) FIX sanitized header nav
- removed message notifications
5) ADD mailer for User
6) EDIT User index view
7) FIX added migration for HABTM user <-> group
8) ADD feature specs
- list users
- remove user
- edit user
9) ADD utility module
- password generator routine