Eliminate unnecessary conversions of option keys

Change-Id: I5f3b267cec0357fe1a1c1a13bafdf3c1f3b6d426

client/src/com/vaadin/client/ui/VFilterSelect.java

          * 
          * @return The key of the item
          */
-        public int getOptionKey() {
-            return Integer.parseInt(key);
+        public String getOptionKey() {
+            return key;
         }
 
         /**
             newKey = "";
         } else {
             // normal selection
-            newKey = String.valueOf(suggestion.getOptionKey());
+            newKey = suggestion.getOptionKey();
         }
 
         String text = suggestion.getReplacementString();

client/src/com/vaadin/client/ui/combobox/ComboBoxConnector.java

             if (optionUidl.hasAttribute("selected")) {
                 if (!getWidget().waitingForFilteringResponse
                         || getWidget().popupOpenerClicked) {
-                    String newSelectedOptionKey = Integer.toString(suggestion
-                            .getOptionKey());
+                    String newSelectedOptionKey = suggestion.getOptionKey();
                     if (!newSelectedOptionKey
                             .equals(getWidget().selectedOptionKey)
                             || suggestion.getReplacementString().equals(