Added scope to facebook api

src/main/java/org/scribe/builder/api/FacebookApi.java

@@ -1,22 +1,34 @@
 package org.scribe.builder.api;
 
 import org.scribe.model.*;
+
 import org.scribe.utils.*;
+import static org.scribe.utils.URLUtils.*;
 
 public class FacebookApi extends DefaultApi20
 {
   private static final String AUTHORIZE_URL = "https://www.facebook.com/dialog/oauth?client_id=%s&redirect_uri=%s";
+  private static final String SCOPED_AUTHORIZE_URL = AUTHORIZE_URL + "&scope=%s";
 
   @Override
   public String getAccessTokenEndpoint()
   {
     return "https://graph.facebook.com/oauth/access_token";
   }
-  
+
   @Override
   public String getAuthorizationUrl(OAuthConfig config)
   {
     Preconditions.checkValidUrl(config.getCallback(), "Must provide a valid url as callback. Facebook does not support OOB");
-    return String.format(AUTHORIZE_URL, config.getApiKey(), URLUtils.formURLEncode(config.getCallback()));
+
+    // Append scope if present
+    if(config.hasScope())
+    {
+     return String.format(SCOPED_AUTHORIZE_URL, formURLEncode(config.getCallback()), formURLEncode(config.getScope())); 
+    }
+    else
+    {
+      return String.format(AUTHORIZE_URL, config.getApiKey(), formURLEncode(config.getCallback()));
+    }
   }
 }