Made sfa use its own logger.
Made sfa use its own logger.

sfa logging was using the root logger which trashed other uses of
logging. Changed sfa logging to use a logger named 'sfa' instead.

tcmitchell/geni-tools,tcmitchell/geni-tools,GENI-NSF/gram,GENI-NSF/gram,plantigrade/geni-tools,GENI-NSF/gram,plantigrade/geni-tools,ahelsing/geni-tools,ahelsing/geni-tools