CB- 5109 Windows 8.1 - InAppBrowser.

https://issues.apache.org/jira/browse/CB-5109
Adds support of 'x-ms-webview' available in Windows 8.1 and Windows Phone 8.1.

Based on https://github.com/Touchit/cordova-plugin-inappbrowser/tree/CB-5109
Thx Maxime LUCE @Touchit