(John Kemp is a Reuters market analyst. The views expressed are his own) By John Kemp LONDON, Feb 5 (Reuters) - Native American communities are often portrayed as victims of avaricious oil and gas drillers and pipeline companies, who despoil the prairie with little thought for sacred sites. In fact, tribes are some of the largest petroleum developers in the United States and are pressing the federal government for more control over drilling on their own territory.