add functionality to add builders to an Environment

lib/rscons/builders/cc.rb

@@ -0,0 +1,4 @@
+module Rscons
+  class CC < Builder
+  end
+end

lib/rscons/builders/program.rb

@@ -0,0 +1,4 @@
+module Rscons
+  class Program < Builder
+  end
+end