use getAttributeNS with android uri

- this fixes issues with apps using a non-default android namespace
  (e.g., com.opera.browser, sha1
  dcb769ca4489e00b7baa951e80f5e661fbfca18c, versionCode: 1600561541)
  where it uses 'ns0' instead of 'android' for prefixes on attributes
  (see https://gist.github.com/dweinstein/c6ccd67e3ccbd2179955) for
  example.
- closes #1