remove oneEach restriction

It is absolutely valid to have multiple iframe or images per area so
remove the oneEach

src/main/resources/hudson/plugins/view/dashboard/Dashboard/configure-entries.jelly

@@ -55,35 +55,31 @@ THE SOFTWARE.
       <f:hetero-list name="topPortlet" hasHeader="true"
                      descriptors="${descriptors}"
                      items="${it.topPortlets}"
-                     addCaption="${%Add Dashboard Portlet to the top of the view}"
-                     oneEach="true"/>
+                     addCaption="${%Add Dashboard Portlet to the top of the view}"/>
     </f:block>
   </f:section>
   <f:section title="${%Portlets in the left column}">
     <f:block>
       <f:hetero-list name="leftPortlet" hasHeader="true"
                      descriptors="${descriptors}"
                      items="${it.leftPortlets}"
-                     addCaption="${%Add Dashboard Portlet to left column}"
-                     oneEach="true"/>
+                     addCaption="${%Add Dashboard Portlet to left column}"/>
     </f:block>
   </f:section>
   <f:section title="${%Portlets in the right column}">
     <f:block>
       <f:hetero-list name="rightPortlet" hasHeader="true"
                      descriptors="${descriptors}"
                      items="${it.rightPortlets}"
-                     addCaption="${%Add Dashboard Portlet to right column}"
-                     oneEach="true"/>
+                     addCaption="${%Add Dashboard Portlet to right column}"/>
     </f:block>
   </f:section>
   <f:section title="${%Portlets at the bottom of the page}">
     <f:block>
       <f:hetero-list name="bottomPortlet" hasHeader="true"
                      descriptors="${descriptors}"
                      items="${it.bottomPortlets}"
-                     addCaption="${%Add Dashboard Portlet to bottom of the view}"
-                     oneEach="true"/>
+                     addCaption="${%Add Dashboard Portlet to bottom of the view}"/>
     </f:block>
     <p/>
   </f:section>