Allow prebuilt generators to get passed (#18)

* if acceptable type is a generator class, allow that to be passed

* version bump

Author: matt-taylor

lib/json_schematize/field_transformations.rb

@@ -20,7 +20,13 @@ def transform_converter_type!
 
     @converter = DEFAULT_CONVERTERS[@acceptable_types[0]]
     if @converter.nil?
-      @converter = ->(val) { @acceptable_types[0].new(val) }
+      @converter = Proc.new do |val|
+        if @acceptable_types[0] < JsonSchematize::Generator && @acceptable_types[0] === val
+          val
+        else
+          @acceptable_types[0].new(val)
+        end
+      end
     end
   end
 

lib/json_schematize/version.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module JsonSchematize
-  VERSION = "0.11.0"
+  VERSION = "0.12.0"
 end