[Add] A test for access to admins should raise MassAssignmentSecurity::Error
[Mod] Modify 'change' link to open in a new tab.
[Add] Add tests to make sure that these links dont't appear when a user isn't signed in.
[Add] A partial for the new and edit form fields.
[Refactor] The new and edit user view with partial.
[Add] Signed-in users have no reason to access the new and create actions.
[Add] A test for forwarding to the default page after friendly forwarding.
[Mod] Must be first sign out, because already_login before filter add to sessions controller.
[Add] Modify the destroy action to prevent admin users from destroying themselves.
[Mod] In the controller use *_url instead of *_path.
[Mod] Modify flash message.
Merge branch '9.6-Exercises'