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)
sorry, I don't like to use return unnecessary return statements, I rather have a single flow of logic and a single exit point, therefore I reuse the ob_ctxs list.

This way if something else needs to happen there in the future I don't have to change the code.

It's this old philosophy from Dijsktra (SESE - Single Entry Single Exit), some people like it, some people don't.