(Editor's note: This story has been updated to include information from a letter sent by House Armed Services Committee Chairman Buck McKeon (R-CA) to Defense Secretary Chuck Hagel.) As Defense Department officials execute their government shutdown plan by furloughing non-excepted government civilians, some officials on Capitol Hill are pointing to the Pay Our Military Act, signed into law by President Obama yesterday, in arguing that such a measure is no longer necessary. "We are trying to get the [DOD]...