Set SSL issue date to one month ago

This fixes an issue where the client trusts the CA, but where the clocks are not
synchronized.
Do not drop unrecognized Authorization headers

The Authorization may contain schemes other than Basic. Before this patch,
"Authorization: GoogleLogin ..." was silently dropped which broke an
application.

After this patch, constructAuthenticationHeader still return null when
challenges are given but negotiation fail (when headers WWW-Authenticate
or Proxy-Authenticate are given). But instead of returning null when
the authorization scheme is unrecognized, return the credentials string (the
string that is given to Proxy-Authorization or Authorization).
Merge pull request #5 from Lekensteyn/fixes

Fixes: SSL issue date and avoid dropping unrecognized Authentication header