Allows user to delete account

* Adds delete button to user show page
* Adds confirm message on submit
* Adds destroy action to users_controller
* Adds :delete resource to routes for users
Secures delete/edit button only if current_user == user

* Adds current user last name to layout/application with link to show page
Requires current_user == user for update and destroy action
Merge pull request #5 from Psychologist-Today/delete_user_profile

Allows user to delete account