[minor] Added an extra compiler so it can be used in Primus

There's no way around this as it needs underscore to be resolved from the modules
directory. Now you can just simply require(ejson/source) and get the source as
string.

source.js

@@ -0,0 +1,29 @@
+'use strict';
+
+var read = require('fs').readFileSync
+  , path = require('path');
+
+//
+// Create a browser stable version of underscore so it can be included in the
+// source of the EJSON library.
+//
+var _ = read(require.resolve('underscore'), 'utf-8').slice(0, -7) + 'root);';
+
+//
+// Remove the module.exports of the EJSON library which has been browserified.
+//
+var EJSON = read(path.join(__dirname, 'index.js'), 'utf-8').slice(16);
+
+//
+// Remove the require statement for underscore and replace it with the full
+// source of the library.
+//
+EJSON = EJSON.replace(/var\s\_\s=\srequire\(\"underscore\"\);/, [
+  _,
+  'var _ = "undefined" !== typeof exports ? exports._ : root._;'
+].join(''));
+
+//
+// Force a global variable and expose the string.
+//
+module.exports = ';var EJSON = '+ EJSON;