Gitlab::Auth and API::APIGuard already check for at least one valid
scope on personal access tokens, so if the scopes are empty the token
will always fail validation.
- Use `TokenAuthenticatable` to generate the personal access token
- Remove a check for `authenticity_token` in application controller;
this should've been `authentication_token`, maybe, and doesn't make
any sense now.
- Have the datepicker appear inline
