Prevent couchdb admin password errors.

Ensure user enters an admin password & provide an error if missing. Also a tweak
to the docs (403 not 401 from couchdb). I found these becuase entered an admin
password I didn't want to use so removed it from npm config, which killed
hoodie start.
Merge pull request #43 from phuu/fix/password-errors

Prevent couchdb admin password errors.