add vendoring with go dep

vendor/github.com/vmware/govmomi/scripts/contributors.sh

@@ -0,0 +1,13 @@
+#!/bin/bash -e
+
+file="$(git rev-parse --show-toplevel)/CONTRIBUTORS"
+
+cat <<EOF > "$file"
+# People who can (and typically have) contributed to this repository.
+#
+# This script is generated by $(basename "$0")
+#
+
+EOF
+
+git log --format='%aN <%aE>' | sort -uf >> "$file"