Add support for SubjectAltName in SSL certificates

[aledbf]

Create a SSL certificate with subjectAltName

$ openssl req \
    -newkey rsa:2048 \
    -x509 \
    -nodes \
    -keyout server.key \
    -new \
    -out server.crt \
    -subj /CN=dev.mycompany.com \
    -reqexts SAN \
    -extensions SAN \
    -config <(cat /etc/ssl/openssl.cnf \
        <(printf '[SAN]\nsubjectAltName=DNS:dev.mycompany.com')) \
    -sha256 \
    -days 3650

Create a secret with the generated certificate

$ kubectl create secret tls mycompany --cert=server.cert --key=server.key

Create an ingress that reference the create SSL certificate

$ echo "
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: mycompany
  namespace: default
spec:
  tls:
    - secretName: mycompany
      hosts:
        - dev.mycompany.com
  rules:
  - host: dev.mycompany.com
    http:
      paths:
      - backend:
          serviceName: http-svc
          servicePort: 80
        path: /
" | kubectl create -f -

Test:

$ minikube ssh
$ curl https://localhost -v -H 'Host: dev.mycompany.com' -k
* TLSv1.2 (OUT), TLS header, Certificate Status (22):
* TLSv1.2 (OUT), TLS handshake, Client hello (1):
* TLSv1.2 (IN), TLS handshake, Server hello (2):
* TLSv1.2 (IN), TLS handshake, Certificate (11):
* TLSv1.2 (IN), TLS handshake, Server key exchange (12):
* TLSv1.2 (IN), TLS handshake, Server finished (14):
* TLSv1.2 (OUT), TLS handshake, Client key exchange (16):
* TLSv1.2 (OUT), TLS change cipher, Client hello (1):
* TLSv1.2 (OUT), TLS handshake, Finished (20):
* TLSv1.2 (IN), TLS change cipher, Client hello (1):
* TLSv1.2 (IN), TLS handshake, Finished (20):
> GET / HTTP/1.1
> Host: dev.mycompany.com
> User-Agent: curl/7.50.1
> Accept: */*
> 
< HTTP/1.1 200 OK
< Server: nginx/1.13.1
< Date: Fri, 23 Jun 2017 00:47:53 GMT
< Content-Type: text/plain
< Transfer-Encoding: chunked
< Connection: keep-alive
< Set-Cookie: route=4c076d0ba212d6bf28bbdac6368e32a1a2fd32a6; Path=/; HttpOnly
< Strict-Transport-Security: max-age=15724800; includeSubDomains;
< 


Hostname: http-svc-82h3l

Pod Information:
	node name:	 minikube
	pod name:	 http-svc-82h3l
	pod namespace:	 default
	pod IP:  	 172.17.0.2

Server values:
	server_version=nginx: 1.13.0 - lua: 10008

Request Information:
	client_address=172.17.0.8
	method=GET
	real path=/
	query=
	request_version=1.1
	request_uri=http://dev.mycompany.com:8080/

Request Headers:
	accept=*/*
	connection=close
	host=dev.mycompany.com
	user-agent=curl/7.50.1
	x-forwarded-for=172.17.0.1
	x-forwarded-host=dev.mycompany.com
	x-forwarded-port=443
	x-forwarded-proto=https
	x-original-uri=/
	x-real-ip=172.17.0.1
	x-scheme=https

Request Body:
	-no body in request-

fixes #548

[k8s-reviewable]

This change is 

[coveralls]

Coverage decreased (-0.3%) to 44.253% when pulling 4ee2bdc on aledbf:tls-alt-names into 103d082 on kubernetes:master.