Add default requires on filterly module

Author: tomeroth

lib/filterly.rb

@@ -1,5 +1,8 @@
-require "filterly/version"
 require 'ast'
+require 'filterly/version'
+require 'filterly/parser'
+require 'filterly/tree'
+require 'filterly/node_builder'
 
 module Filterly
   # Your code goes here...