Ignores appengine

The appengine imports cause govendor to fail since it's imported as
"appengine". We get failures like:

    Error: Package "appengine" not a go package or not in GOPATH.

If we ignore it, the issue goes away and we can still comple

vendor/vendor.json

@@ -1,6 +1,6 @@
 {
 	"comment": "",
-	"ignore": "test",
+	"ignore": "test appengine",
 	"package": [
 		{
 			"checksumSHA1": "/WG++Jij8INZ80tER+FAiIDMmws=",