Scrapy errors due to decompression attempt based on Content-Encoding

[BurnzZ]

For Zyte API requests with httpResponseHeader=True, some websites would return headers like Content-Encoding: gzip.

In the current setup, all of the headers in the httpResponseHeader from Zyte API response is used to create the Response in the Download Handler.

Now, when the response containing the Content-Encoding: gzip header is processed by the Downloader Middlewares, the scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware errors out since it's attempting to decompress the gzipped response.

This is not the case since Zyte API already decompressed the contents.

[BurnzZ]

Closing this as #14 has been merged. However, it won't be merged to master until #10 is merged as well

[kmike]

This is fixed now.