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)
I don't mind which one you choose, but please let's not have redundant long switches. I agree `--db-path` is better; if you drop `--database`, remember to patch `openbazaar_daemon`.