removed ref to configuring resolve.conf which is not needed with current install
added line to ensure that .google_authenticator file permissions are set to 400
Merge pull request #233 from dolanjs/fix-ubuntu-config-doc

Remove obsolete documentation from ubuntu_config.md, fixes #216
Merge pull request #234 from dolanjs/fix-google-auth-permissions

Ensure .google_authenticator file permissions are set. Fixes #201