Make it possible to disable colors

Fixes #76

lib/util/hogan-colors.js

@@ -9,8 +9,13 @@
 var colors = require('colors');
 var hogan  = require('hogan.js');
 var _      = require('lodash');
+var nopt   = require('nopt');
 
 module.exports = hogan.Template.prototype.renderWithColors = function (context, partials, indent) {
+  if (nopt(process.argv).color === false) {
+    colors.mode = 'none';
+  }
+
   context = _.extend({
     yellow : function (s) { return s.yellow },
     green  : function (s) { return s.green  },