Switch to using the dep tool and update all the dependencies

vendor/google.golang.org/grpc/backoff_test.go

@@ -0,0 +1,11 @@
+package grpc
+
+import "testing"
+
+func TestBackoffConfigDefaults(t *testing.T) {
+	b := BackoffConfig{}
+	setDefaults(&b)
+	if b != DefaultBackoffConfig {
+		t.Fatalf("expected BackoffConfig to pickup default parameters: %v != %v", b, DefaultBackoffConfig)
+	}
+}