Be able to set switch states in JavaScript

[tobych]

I want to set switch states from the JavaScript console to help debug my code.

[jsocol]

Actually I think this has always been possible:

> console.log(waffle.FLAGS);
> waffle.FLAGS['my_flag'] = true;
> waffle.flag_is_active('my_flag');

Similar for SWITCHES and SAMPLES.

I'm facepalming pretty hard I never noticed that.

[jsocol]

Sorry, not always, just since #97!