HTTPS call causes E500, if cannot resolve DNS record

[tkohegyi]

Internal error (E500) occurs in proxy if DNS record cannot be resolved during a HTTPS call.

Answer (incorrect):
14:05:09.380 [SocketListener0-1] DEBUG n.l.b.p.s.SeleniumProxyHandler - CONNECT: .....
14:05:09.418 [SocketListener0-1] DEBUG n.l.b.p.s.SeleniumProxyHandler - error during handleConnect
java.net.UnknownHostException: No such host is known (....)
14:05:09.422 [SocketListener0-1] DEBUG n.l.b.p.jetty.http.HttpConnection - RESPONSE:
HTTP/1.1 500 java%2Enet%2EUnknownHostException%3A+No+such+host+is+known+.....

In case of HTTP, E404 is used (let say it is correct):
14:03:58.604 [SocketListener0-1] DEBUG n.l.b.p.jetty.http.HttpConnection - RESPONSE:
HTTP/1.1 404 Not Found

quickest test command (if proxy is running on localhost and at port 9092):
curl --insecure -X GET https://no.dns.record -x 127.0.0.1:9092
result: curl: (56) CONNECT tunnel failed, response 500

[tkohegyi]

This fix addresses it: 89f7761