Support loading images from local storage

closes #276

android/app/src/main/java/com/reactnativenavigation/react/ImageLoader.java

 package com.reactnativenavigation.react;
 
+import android.graphics.drawable.BitmapDrawable;
 import android.graphics.drawable.Drawable;
+import android.net.Uri;
 
 import com.reactnativenavigation.NavigationApplication;
 
 public class ImageLoader {
+    private static final String FILE_SCHEME = "file";
 
     public static Drawable loadImage(String iconSource) {
         if (NavigationApplication.instance.isDebug()) {
             return JsDevImageLoader.loadIcon(iconSource);
         } else {
-            return ResourceDrawableIdHelper.instance.getResourceDrawable(NavigationApplication.instance, iconSource);
+            Uri uri = Uri.parse(iconSource);
+            if (isLocalFile(uri)) {
+                return loadFile(uri);
+            } else {
+                return loadResource(iconSource);
+            }
         }
     }
+
+    private static boolean isLocalFile(Uri uri) {
+        return FILE_SCHEME.equals(uri.getScheme());
+    }
+
+    private static Drawable loadFile(Uri uri) {
+        return new BitmapDrawable(NavigationApplication.instance.getResources(), uri.getPath());
+    }
+
+    private static Drawable loadResource(String iconSource) {
+        return ResourceDrawableIdHelper.instance.getResourceDrawable(NavigationApplication.instance, iconSource);
+    }
 }