Upgrade Audience Network adapter for Prebid 1.0

[lovell]

As requested by @mjacobsonny and paid for by Facebook.

In addition to 100% unit test branch coverage, I've manually tested this using pbjs_debug=true and everything appears to be working end-to-end.

The two biggest gotchas I ran into that required me to dig into the new Prebid source code to determine expected behaviour were:

1. The inconsistent properties (type=method, endpoint=url?) of the ServerRequest expected from buildRequests() documented at http://prebid.org/dev-docs/bidder-adapter-1.html#building-the-request
2. The need to include the original bidId passed to buildRequests() as the differently-named requestId property of the bidObject returned by interpretResponse().

[dbemiller]

hey @lovell, can you make these changes against master? It'll reduce merge conflicts and make the branches easier for us to maintain during the 1.0 transition.

Thanks!

[dbemiller]

For some subtle reasons, you shouldn't set bidderCode in here. It breaks adapter aliasing.

Our docs have been updated to reflect this... but sorry for the confusion all the same.

[dbemiller]

agh... sorry about this, but one more change, because #1742 got merged before we could get this in.

The first argument to interpretResponse has been changed, and now looks like this:

{
  body: responseBody,
  headers: {
    get: function(header) { /* returns a header from the HTTP response */ }
  }
}

Could you also pull master and update that?

[lovell]

Updated and rebased against master but other, unrelated unit tests are failing at the moment.