Add additional check for old SSL certificates

[aledbf]

What this PR does / why we need it:

fixes #1770

[k8s-reviewable]

This change is 

[coveralls]

Coverage decreased (-0.4%) to 36.841% when pulling 3ad53ec46aca6914961143bdaf2254baf6df7a35 on aledbf:verifyHostname into 37a230c on kubernetes:master.

[coveralls]

Coverage decreased (-0.4%) to 36.881% when pulling 930bd7f on aledbf:verifyHostname into 37a230c on kubernetes:master.

[rikatz]

@aledbf Tested here, it worked fine :)

Maybe we could also improve the error messages, they look pretty confuse, like:

unexpected error validating SSL certificate gestaoip-p/secret-tls for host systemx.domain.tld. Reason: x509: certificate is valid for systemx.domain.tld, not systemx.domain.tld

But I think THIS could be a TODO, so LGTM here :)

@jcmoraisjr FYI

[cmosetick]

Has this been tested with Wildcard SSL certificates??
I'm seeing some issues with ingress nginx when Java 8 and Maven hit a ingress with a wild card certificate for a Nexus artifactory.
We were not seeing this issue with gcr.io/google_containers/nginx-ingress-controller:0.9.0-beta.15
but we have issues with gcr.io/google_containers/nginx-ingress-controller:0.9.0

[aledbf]

@cmosetick yes. Please post the log from the ingress controller and the output of
openssl x509 -in <cert> -text (remobing the cert and sensitive information)

Edit: open a new issue please