Fixes #177: adds HostKeyCallback to ssh.ClientConfig

This is needed since https://github.com/golang/go/issues/19767
diff --git a/examples/buffered-read-benchmark/main.go b/examples/buffered-read-benchmark/main.go
index 32c4d1f..36ac6d7 100644
--- a/examples/buffered-read-benchmark/main.go
+++ b/examples/buffered-read-benchmark/main.go
@@ -42,6 +42,7 @@
 	config := ssh.ClientConfig{
 		User: *USER,
 		Auth: auths,
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
 	}
 	addr := fmt.Sprintf("%s:%d", *HOST, *PORT)
 	conn, err := ssh.Dial("tcp", addr, &config)
diff --git a/examples/buffered-write-benchmark/main.go b/examples/buffered-write-benchmark/main.go
index 0c38db6..d1babed 100644
--- a/examples/buffered-write-benchmark/main.go
+++ b/examples/buffered-write-benchmark/main.go
@@ -42,6 +42,7 @@
 	config := ssh.ClientConfig{
 		User: *USER,
 		Auth: auths,
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
 	}
 	addr := fmt.Sprintf("%s:%d", *HOST, *PORT)
 	conn, err := ssh.Dial("tcp", addr, &config)
diff --git a/examples/streaming-read-benchmark/main.go b/examples/streaming-read-benchmark/main.go
index dc901e9..87afc5a 100644
--- a/examples/streaming-read-benchmark/main.go
+++ b/examples/streaming-read-benchmark/main.go
@@ -43,6 +43,7 @@
 	config := ssh.ClientConfig{
 		User: *USER,
 		Auth: auths,
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
 	}
 	addr := fmt.Sprintf("%s:%d", *HOST, *PORT)
 	conn, err := ssh.Dial("tcp", addr, &config)
diff --git a/examples/streaming-write-benchmark/main.go b/examples/streaming-write-benchmark/main.go
index 07a9ddb..8f432d3 100644
--- a/examples/streaming-write-benchmark/main.go
+++ b/examples/streaming-write-benchmark/main.go
@@ -43,6 +43,7 @@
 	config := ssh.ClientConfig{
 		User: *USER,
 		Auth: auths,
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
 	}
 	addr := fmt.Sprintf("%s:%d", *HOST, *PORT)
 	conn, err := ssh.Dial("tcp", addr, &config)