Error in module.options.guides in MapModule

[jywarren]

I realized we hadn't copied in the new default mapModule: true into the examples/index.html file, but upon adding it, i see this error:

PublicLab.Editor.js:21758 Uncaught TypeError: Cannot read property 'forEach' of undefined
    at Class._module.build (PublicLab.Editor.js:21758)
    at Class.init (PublicLab.Editor.js:21725)
    at Class.prototype.(anonymous function) [as init] (http://localhost:3001/dist/PublicLab.Editor.js:16752:28)
    at new Class (PublicLab.Editor.js:16765)
    at Class.init (PublicLab.Editor.js:20682)
    at new Class (PublicLab.Editor.js:16765)
    at index.html:339
    at index.html:345

This is actually also affecting the PublicLab.org production site, so it's a bit urgent.

[jywarren]

Reproduced in a test here: #300