Delete assets before extraction

android/java/lib/src/main/java/com/arieslabs/assetbridge/Assetbridge.java

@@ -37,6 +37,7 @@ public class Assetbridge {
 
             // iterate on the files...
             for(String asset : assets) {
+                delete(datadir + "/" + asset);
                 copyAssetFolder(am, asset, datadir + "/" + asset);
             }
 
@@ -50,6 +51,13 @@ public class Assetbridge {
 
     }
 
+    public static void delete(String dest) {
+        File destfh = new File(dest);
+        if (destfh.exists()) {
+            destfh.delete();
+        }
+    }
+
 
     public static void copyAssetFolder(AssetManager am, String src, String dest)
     	throws IOException {