Added replace parameter for setText

Requires https://github.com/admc/wd/pull/333 to be pulled first.

I also want to create a test for this in keyboard-specs.js but I can add that in another pull. 

Tested with the wd.js change and it works for me.
@jlipps Yeah, that's what I was saying. Why call join? Why does the string need to be formatted like x and what will it look like? Your comment sums it up.