Openbazaar python launcher

new pull request after 1st round of reviews.
Thanks @Renelvon this has the merged changes from your repo.

(@Renelvon I kept that REVERT commit you put there as I'm not sure I understood what was right or wrong about it, I figured it'd be easier to fix here now)
question: what executes checkstyle.sh? 
and how do we know it's in fact being executed from inside virtualenv? 

if there a way to check if we're being executed from `virtualenv`?

as far as we know this script is a bash script on the openbazaar root folder, being executed with `/bin/bash`, and pylint would be executed from here, not from within a python script which might be started from ` ./env/bin/python`