#190 fix "Cannot read property 'headers' of undefined"

[d9k]

[D-Pow]

This is actually a very important PR. Can someone please review it?

It only has a couple of lines changed, and changed in such a way that it actually reads the response headers instead of a makeshift hack around setting a global headers object.

Not to mention that global variables are substantially more prone to bugs than generated/object instance fields. i.e. var headers should be response.headers and/or get headers() {...}.

[AlexanderKidd]

Can this get merged in or are no new releases planned?