Changed app.openBrowser to use system's default browser instead of Cordova InAppBrowser.

The custom URL handler doesn't work when following links having the evothings:// protocol from within a Cordova InAppBrowser instance. Therefore the app.openBrowser function has been modified to instead open URLs in the system's default browser.

For information regarding Cordova's window.open parameters, see https://github.com/apache/cordova-plugin-inappbrowser/blob/master/doc/index.md.