Papi: Rename methods argument

The argument name 'csit_papi_command' must be unique enough as it cannot
be repeated in kwargs.
  - PapiExecutor.add(self, csit_papi_command, **kwargs)
  - PapiHistory.add_to_papi_history(node, csit_papi_command, papi=True, **kwargs)

Change-Id: I243a20d6f03befb149891c37a88e0e6359ea2940
Signed-off-by: Tibor Frank <tifrank@cisco.com>