Fixes #15 by adding a password check for new / edited users.
Merge branch 'master' of github.com:gfarrell/WPRavenAuth

* 'master' of github.com:gfarrell/WPRavenAuth:
  Update README.md
  Update README.md
  Update README.md
Complete #16
Fixes #16 and makes salt private (can't see why it would need to be public)