Ensure gzipped responses not truncated

Ensure that gzipped responses are not truncated when proxied.
Ensure :decompress-body is always false

Remove :decompress-body from the http-opts map passed into
wrap-proxy, as if this is ever true a gzipped response will
be truncated.
Address PR comments

Add a comment explaining the decision to remove :decompress-body
from the http-opts map.
Merge pull request #8 from fpringvaldsen/gzip-fix

(PE-5594) Stop ring-middleware from truncating gzipped responses