Add cancan and rolify; add sanitized params to sign_up; include cancan ability class; creates users_roles table; edit temporarily new user view and allows new users sign_up; defines rails_admin to use cancan; defines rolify to create new roles easily.
Make permissions work. Need some beauty improvements; ignore rbenv configurations; create table roles migration changed.
Improves permissions definition in ability.
Changes relationship between users and roles.

Changes the relationship from has_and_belongs_to_many :users_roles to belongs_to :role; not using anymore intermediate table 'users_roles'.
Changes the create_table_roles migration to not create the 'users_roles' table.
Improves permissions

Removes 'perm_temp' field.
Makes permissions rendered by a partial.
Merge and test.

Test - Unauthorized fields in permissions
Merge of develop in feature/authorization
Merge branch 'develop' into feature/authorization
Fixes permission test.
fix roles migration
Merge branch 'develop' into feature/authorization
Merge branch 'develop' into feature/authorization
populate rake
permissions pretty screen
Merge branch 'feature/authorization' into develop