Allow parenthesized xpath expressions

The findStrategy helper identifies which method to use as specific selector based on characteristics for the given selector.

But it fails for paranthesized xpath queries. These queries are useful if you want to address a specific element by position, but idependently of the parant element.

i.e. the xpath query "(//div)[7]" find's the overall 7th div in the dom, independently of parents/siblings etc.