[CB-2213] Added a test for NATIVE_URI.

This test uses the camera to get the native URI of an image from the device's photo library, and uses that URI to display the file's info.

Adding this one for now.  It works on iOS with my local implementation of CDVFile.getFileMetadata.  After this, I'll submit a pull request for a bunch of tests that don't work; from there, I'll gradually add functionality to cordova-ios.