Give a user friendly message to "napp create" if user hit CTRL+C

[rmotitsuki]

When creating a napp, if the user presses CTRL + C while typing the user name or the napp name, the program throws an exception.
The user should get a more friendly response.

Please, insert your NApps Server username: ^CTraceback (most recent call last):
  File "./kytos", line 43, in <module>
    parse(argv)
  File "/home/rogerio/projects/env_kytos_utils/lib/python3.6/site-packages/kytos/cli/commands/napps/parser.py", line 51, in parse
    call(sys.argv[2], args)
  File "/home/rogerio/projects/env_kytos_utils/lib/python3.6/site-packages/kytos/cli/commands/napps/parser.py", line 61, in call
    func(args)
  File "/home/rogerio/projects/env_kytos_utils/lib/python3.6/site-packages/kytos/cli/commands/napps/api.py", line 88, in create
    NAppsManager.create_napp(meta_package=args.get('--meta', False))
  File "/home/rogerio/projects/env_kytos_utils/lib/python3.6/site-packages/kytos/utils/napps.py", line 364, in create_napp
    username = input('Please, insert your NApps Server username: ')
  File "/home/rogerio/projects/env_kytos_utils/lib/python3.6/site-packages/engineio/client.py", line 41, in signal_handler
    return original_signal_handler(sig, frame)
KeyboardInterrupt