Switch to github.com/golang/dep for vendoring

Signed-off-by: Mrunal Patel <mrunalp@gmail.com>

vendor/github.com/Microsoft/hcsshim/layerexists.go

@@ -0,0 +1,30 @@
+package hcsshim
+
+import "github.com/Sirupsen/logrus"
+
+// LayerExists will return true if a layer with the given id exists and is known
+// to the system.
+func LayerExists(info DriverInfo, id string) (bool, error) {
+	title := "hcsshim::LayerExists "
+	logrus.Debugf(title+"Flavour %d ID %s", info.Flavour, id)
+
+	// Convert info to API calling convention
+	infop, err := convertDriverInfo(info)
+	if err != nil {
+		logrus.Error(err)
+		return false, err
+	}
+
+	// Call the procedure itself.
+	var exists uint32
+
+	err = layerExists(&infop, id, &exists)
+	if err != nil {
+		err = makeErrorf(err, title, "id=%s flavour=%d", id, info.Flavour)
+		logrus.Error(err)
+		return false, err
+	}
+
+	logrus.Debugf(title+"succeeded flavour=%d id=%s exists=%d", info.Flavour, id, exists)
+	return exists != 0, nil
+}