MB-28665: Restrict client certificate auth...
MB-28665: Restrict client certificate auth...

...only to https requests.

The AuthWebCreds API will be called by services for both http and
https requests. Currently, an attempt was being made to authenticate
using client certificates unconditionally which would be a problem
for http requests. The fix is to ignore client cert auth for http
requests.

Change-Id: I36f0d71cedd5073ccc0040a03845d7dc445e3acd
Reviewed-on: http://review.couchbase.org/91025
Well-Formed: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Tested-by: Ajit Yagaty <670a5cadfa9668cb910cc315f6527868cd5ab42a@couchbase.com>
Reviewed-by: Artem Stemkovski <15a0730a27c69f62ab86f2b6c639fca202166c02@couchbase.com>

couchbase/cbauth,couchbase/cbauth