Green tests on iOS 8.1/Xcode 6.1/ruby 2.0

I'd say the most non-obvious fix is adding `platformVersion = "8.1"` to appium.txt. That is required to set context to WEBVIEW, since there is a little bug in Appium server. I'll try to make the fix later and then we can remove platformVersion back.

PS: Probably it's necessary to update some docs accordingly.