Adding pulp_streamer compression check tests
The problem occurs only for content that can be compressed with gzip.
Nectar, the download library inside pulp workers, advertises that it can
receive content compressed using gzip. When the worker asks the web server
for one of the distribution files, the web server responds with the files
compressed using gzip. The worker uses nectar to decode the file and then
writes it to disk. The same nectar code is used in the streamer. When
the streamer is passing along the file, it is passing it along in the
decoded form. When the worker gets this data during the
``deferred_download`` task or the ``download`` task, it is attempting to
decompress it, but the streamer had already done that.
Adding a test to verify the content being published is compressed