Fix tapping for iOS 7.1/Xcode 6.x

When using Xcode 6.x (tried with 6.0.1, 6.1, and 6.2 beta) with a 7.1 simulator, the call to `hasKeyboardFocus()` mostly returns `1` even when the keyboard is not focused, so `tap` was never called. There don't seem to be any ill-effects to tapping always.

See appium/appium#4243.