VOL-518 add missing dependency.

Change-Id: Ibfc0a2904104bfcfe9aa462ad6dd9fc4ef5abb04
diff --git a/unum/vendor/vendor.json b/unum/vendor/vendor.json
index 8fc528a..117d870 100644
--- a/unum/vendor/vendor.json
+++ b/unum/vendor/vendor.json
@@ -283,6 +283,12 @@
 			"revisionTime": "2017-09-01T22:45:32Z"
 		},
 		{
+			"checksumSHA1": "DpsruMRlfaXitPiELMUatEOMh1k=",
+			"path": "github.com/tatsushid/go-fastping",
+			"revision": "d7bb493dee3e090e2ffb6914adddf17c1e7c026c",
+			"revisionTime": "2016-01-08T17:53:29Z"
+		},
+		{
 			"checksumSHA1": "nqWNlnMmVpt628zzvyo6Yv2CX5Q=",
 			"origin": "github.com/Sirupsen/logrus/vendor/golang.org/x/crypto/ssh/terminal",
 			"path": "golang.org/x/crypto/ssh/terminal",