Use a vendor directory for repeatable builds - fixes #816

This is using godep to manage the vendor directory.

vendor/google.golang.org/appengine/internal/regen.sh

@@ -0,0 +1,36 @@
+#!/bin/bash -e
+#
+# This script rebuilds the generated code for the protocol buffers.
+# To run this you will need protoc and goprotobuf installed;
+# see https://github.com/golang/protobuf for instructions.
+
+PKG=google.golang.org/appengine
+
+function die() {
+	echo 1>&2 $*
+	exit 1
+}
+
+# Sanity check that the right tools are accessible.
+for tool in go protoc protoc-gen-go; do
+	q=$(which $tool) || die "didn't find $tool"
+	echo 1>&2 "$tool: $q"
+done
+
+echo -n 1>&2 "finding package dir... "
+pkgdir=$(go list -f '{{.Dir}}' $PKG)
+echo 1>&2 $pkgdir
+base=$(echo $pkgdir | sed "s,/$PKG\$,,")
+echo 1>&2 "base: $base"
+cd $base
+for f in $(find $PKG/internal -name '*.proto'); do
+	echo 1>&2 "* $f"
+	protoc --go_out=. $f
+done
+
+# Fix up import lines.
+# This should be fixed upstream.
+# https://code.google.com/p/goprotobuf/issues/detail?id=32
+for f in $(find $PKG/internal -name '*.pb.go'); do
+  sed -i '/^import.*\.pb"$/s,/[^/]*\.pb"$,",' $f
+done