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)
If you drop redundant long flags in the `parser`, don't forget to update this, too. Anyway, the `usage` message is too tedious to review extensively, so I will basically skip it. I plan to DRY it once we merge you.