Edit action and views

- edit and update actions in users controller
- handle if user isn't signed in
- ensure correct user (called method in sessions helper)

On branch feature/user-updates
Changes to be committed:
	modified:   app/controllers/users_controller.rb
	modified:   app/views/layouts/_header.html.haml
	new file:   app/views/users/edit.html.haml

Changes not staged for commit:
	modified:   app/controllers/sessions_controller.rb
	modified:   app/helpers/sessions_helper.rb
Ensure correct user, friendly forwarding

On branch feature/user-updates
Changes to be committed:
	modified:   app/controllers/sessions_controller.rb
	modified:   app/helpers/sessions_helper.rb
add will paginate gems for later (just in case)
Merge branch 'feature/user-updates' into develop

* feature/user-updates:
  add will paginate gems for later (just in case)
  Ensure correct user, friendly forwarding
  Edit action and views