remove extraneous CRLF after message-body

RFC2616 section 4.1 (http://www.ietf.org/rfc/rfc2616.txt):
"... an HTTP/1.1 client MUST NOT preface or follow a request
with an extra CRLF."
(cherry picked from commit d0e8e715b409457364c952e305e7f296653ae8cc)
make installers: fix quoting for windows/bash ssh
(cherry picked from commit fd487b86a316db29d2d03dc6a665beb21f958371)
Add rackunit HISTORY.txt for version 6.0.
(cherry picked from commit ec75e9ae0838dfb25e5c92a4c011bd63145cbbdc)