take advantaged of 'x' flag when opening files to workaround tarfile issue with python 3.3
take advantaged of 'x' flag when opening files to workaround tarfile issue with python 3.3

iriark01/yotta,stevenewey/yotta,BlackstoneEngineering/yotta,ntoll/yotta,ARMmbed/yotta,iriark01/yotta,stevenewey/yotta,theotherjimmy/yotta,eyeye/yotta,eyeye/yotta,theotherjimmy/yotta,autopulated/yotta,ARMmbed/yotta,BlackstoneEngineering/yotta,ntoll/yotta,autopulated/yotta