Revert "Fix the Android implementation to return a file path, not an Uri path"

I was actually wrong on this.

Fixes #15

my problem i was having is you can't do new File(uri) but it's normal, it's not a file path, it's a Uri,
if you are sure you have a file uri, you can do new File(Uri.parse(uri).getPath()) but I guess best is to get a input stream from the Uri or keep using Uri..

This reverts commit a85cf9629a.

android/src/main/java/fr/greweb/reactnativeviewshot/ViewShot.java

             if ("file".equals(result)) {
                 os = new FileOutputStream(output);
                 captureView(view, os);
-                promise.resolve(output.getAbsolutePath());
+                String uri = Uri.fromFile(output).toString();
+                promise.resolve(uri);
             }
             else if ("base64".equals(result)) {
                 os = new ByteArrayOutputStream();