Write the rankfile with a python file wrapper in the launcher
Write the rankfile with a python file wrapper in the launcher

- The python file wrapper accepts strings, os.write accepts bytes.
  Use the file wrapper to take care of encoding for the write.

Signed-off-by: Daniel Wilson <c0a46a3457096bdbf302f01d2d37cf72d30c651c@intel.com>
Change-Id: I2d88c8f63ddb7c37fcdd432b056fc90901fa8482

cmcantalupo/geopm,cmcantalupo/geopm,cmcantalupo/geopm,geopm/geopm,geopm/geopm,cmcantalupo/geopm,geopm/geopm,cmcantalupo/geopm,geopm/geopm,geopm/geopm