Add Keys for FlipperObject

Summary: This adds ability to iterate over FlipperObject before sending it to be processed on Flipper desktop

Reviewed By: mweststrate

Differential Revision: D21214901

fbshipit-source-id: a6186a42004f1afb70889a395b1df037447f9881

android/src/main/java/com/facebook/flipper/core/FlipperObject.java

@@ -8,6 +8,7 @@
 package com.facebook.flipper.core;
 
 import java.util.Arrays;
+import java.util.Iterator;
 import javax.annotation.Nullable;
 import org.json.JSONArray;
 import org.json.JSONException;
@@ -85,6 +86,10 @@ public class FlipperObject {
     return mJson.has(name);
   }
 
+  public Iterator<String> keys() {
+    return mJson.keys();
+  }
+
   public String toJsonString() {
     return toString();
   }