(PE-5640) Add proxy redirect support

Have proxied requests follow redirects on POST requests by
default. Add tests for proxy redirect functionality.
(PE-5640) Fix test

Fix test of redirect to non-proxied path, as it was passing
erroneously.
Merge pull request #7 from fpringvaldsen/PE-5640-proxy-redirect

(PE-5640) Add proxy redirect support
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.