Handle compressed responses from Dogtag
We currently accept compressed responses for some Dogtag resources,
via an 'Accept: gzip, deflate' header. But we don't decompress the
received data. Inspect the response Content-Encoding header and
decompress the response body according to its value.
The `gzip.decompress` function is only available on Python 3.2 or
later. In earlier versions, it is necessary to use StringIO and
treat the compressed data as a file. This commit avoids this
complexity. Therefore it should only be included in Python 3 based
releases.
Fixes: https://pagure.io/freeipa/issue/7563
Reviewed-By: Christian Heimes <cheimes@redhat.com>