Settings

added the `settings` api, plus implemented the setting for xpath compression.
added docs and tests

will squash once approved of course,

Oh, also had to add to wd.js to get the tests working. If we are ok with my implementation I'll push there. In the meantime you can clone [my fork of wd.js](https://github.com/jonahss/wd).

And then I'm going to go and update the rest of the clients....

(of course I'll squash, once we're through here ;)
My misunderstanding was I thought setCompressedLayoutHierarchy() only affected the output of dumpXMLHierarchy() but it's much more than that, it affects all uiautomator searching a traversing.
So I need to change it to be a solid toggle for the entire bootstrap, not just the `find` and `source` commands.
And if it applies to all commands, it doesn't make sense to have it be passed as a command param.