rgw: fix a few warnings

Adjust data types

Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>
Makefile.am: change some cors rules

The cors unitest should be a standalone test (not part of the make
unitests) as it requires having a running gateway and needs input params
to run correctly.
Also update missing header files.

Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>