update for Pixate free edition

lib/motion/project/pixate.rb

@@ -21,15 +21,15 @@ class PixateConfig
   private
 
   def create_code
-    unless @user && @key
-      raise "Need to configure `app.pixate.user' and `app.pixate.key' variables"
+    license = ""
+    if @user && @key
+      license = "PXEngine.licenseKey('#{@key}', forUser:'#{@user}')\n"
     end
 
     code = <<EOF
 # This file is automatically generated. Do not edit.
 
-PXEngine.licenseKey('#{@key}', forUser:'#{@user}')
-
+#{license}
 def style(str)
   PXStylesheet.styleSheetFromSource(str, withOrigin:0)
   PXStylesheet.applyStylesheets