Make partial! consistent with render signature

lib/jbuilder_template.rb

@@ -7,11 +7,18 @@ def initialize(context)
     @context = context
     super()
   end
-
-  def partial!(partial_name, options = {})
-    @context.render(partial_name, options.merge(:json => self))
+
+  def partial!(options, locals = {})
+    case options
+    when Hash
+      options[:locals] ||= {}
+      options[:locals].merge!(:json => self)
+      @context.render(options)
+    else
+      @context.render(options, locals.merge(:json => self))
+    end
   end
-  
+
   private
     def _new_instance
       __class__.new(@context)