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 ;)
yes, that point is absolutely correct. can't think of why we'd want to return an array. i think the appropriate return value for an update operation is `null` anyway; the operation itself shouldn't return the settings object--that's the job of getSettings