Allow chromeOptions method

Added a way to look for chromeOptions that will add in undefined arguments but still let us set the ones we need. Added a deprecation message to the old method and removed it from documentation.
oops, one more thing. pretty small, but this needs to be:

```js
if (typeof caps.chromeOptions[option] === "undefined") {
```

since within functions you can actually redefine `undefined`:

```
~/C/appium-jlipps git:master ❯❯❯ node
> var f = function() {
... var undefined = 'foo';
... var x;
... console.log(x === undefined);
... };
undefined
> f();
false
undefined
```