Use a vendor directory for repeatable builds - fixes #816

This is using godep to manage the vendor directory.

vendor/github.com/stretchr/testify/http/test_round_tripper.go

@@ -0,0 +1,17 @@
+package http
+
+import (
+	"github.com/stretchr/testify/mock"
+	"net/http"
+)
+
+// TestRoundTripper DEPRECATED USE net/http/httptest
+type TestRoundTripper struct {
+	mock.Mock
+}
+
+// RoundTrip DEPRECATED USE net/http/httptest
+func (t *TestRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	args := t.Called(req)
+	return args.Get(0).(*http.Response), args.Error(1)
+}