FIX: correction to popen call returning bytestream

[barbequesauce]

Per #400 Thank you @SenorSmartyPants

[SenorSmartyPants]

Looks like it should fix it to me. Ready to try it out.

[SenorSmartyPants]

All Popen calls should be updated.

[evilhero]

No need to update any Popen calls. This is a logger error, pure & simple. Modifying the line:
logger.fdebug("Script result: " + out)
to:
logger.fdebug("Script result: %s" % out)
would resolve it.

I should also mention that while the above logger line would fix it, adding text=true shouldn't do anything to harm any part of the post-processing module as far as I'm aware (not sure if that modifies some of the return bytes that we check later, but w/e). But again, the other places we use Popen have already been tested, and work as intended - so no need to change those in case the results are modified which causes code changes down the line.

[SenorSmartyPants]

I'm cool with whichever fix that gets implemented. Just want to write more post processing scripts and have them run. Thanks for all your work.