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 don't think `Setting this abbreviation` makes sense. What about `Enabling this option`? Also as mentioned on the previous pull request, I think the setting should be called `discardNotImportantViews`. `xpathCompression` isn't an accurate description of what's happening.