def perform!(email, password, &block)
      login_required
      CaTissue::Database.current.open(email, password, &block)
    end
def perform!(email, password, &block)
      login_required
      CaTissue::Database.current.open(email, password, &block)
    end
Runs the given caTissue operation block with the given caTissue credentials.

 @yield (see #protect!)
 @return [String, nil] the status message