Added some code generation that hangs the helpers off the geddy global in the client and also handles the exports issue

This is a continuation of pull request #516.

Now the shared helper file (e.g. app/helpers/test.shared.js) looks like this:

    exports.testSharedHelpers = function() {
      return '---------------Testing shared helpers---------------';
    };

And the client side access looks like this:

    console.log(geddy.helpers.testSharedHelpers());

Definitely cleaner.  Thanks for the suggestions.