Add Settings api, and xpathCompression setting for Android

Same as last, time, you need to use my fork of wd.js to run the tests...
I mentioned it in an earlier comment on the previous PR. I just adopted the current way it's done. But it should be refactored so they automatically inherit not just these methods, but all the deviceCommon methods. Or something.

You refactor suggestion on the mailing list address this, right?