Use universal_newlines to force default encoding
Use universal_newlines to force default encoding

The 'encoding' param for Popen was not added until
Python 3.6, so this breaks using the CLI on 2.7
which is the most common version for users. Forcing
'universal_newlines' makes Py3 return STDOUT and STDERR
as stings like Py2.7, so this seems like the least
hacky work-around.

racker/fleece,racker/fleece