Print welcome prompt after ZeroRPC services start.

I think this makes it clearer to the user that the script isn't somehow hanging
when starting the SearchService.
Minor changes to README.md.

* Update Vagrant download link.
* ./inbox sync start expects an account ID, not an email address, so use
  ./inbox add instead.
Merge pull request #3 from emfree/master

Tweaks to README.md and inbox script