Add autoWebview capability

Milestone 1.2 issue #2715

Allow user to enter directly into webview context. Adds universal capability `autoWebview` (`true`/`false`) and Android capability `autoWebviewTimeout` (in seconds, defaults to `2`), to set hot long to wait before checking for the webview. 

Also fixes Android/Selendroid webview tests.
I think we need to add another test to this conditional. We only want to navToViewThroughFavorites if we have ios >= 7, are not on a real device, AND are automating safari. In a typical hybrid app, there will be no favorites. Or do you take care of this elsehow?