Breaking changes:

* rmapi: Upload no longer returns generation as it's not very useful

Other changes:

* rmapi: Add helper functions to APIResponse to for better json
  unmarshaling and preserve potential additional http headers for
  requests.
* rmapi: Handle double quoted expires json timestamp from api 1.5
  responses.
* readable: Add support to nitro-lazy-src images.
* readable: Fix a bug of handling relative image urls.
* readable&birds: Add generated meta info to final html.