Added cucumber tests for ssh-keys
Added base for ssh-key management of users
Added implementation of sshkey resource

- Removed unnecessary views and controller methods, as well as modified
  routes to fit that
- Added authentication filter for sshkey resource
- Modified sshkey resource so their path is /users/ssh_keys
- Not yet testest with cucumber
Corrected ssh-key cucumber code

- There were two features in one feature file