Code review comment for lp:~wallyworld/goose/RunServer-userData-fix

I think this is the right fix. ISTR that if you use []byte in a data
structure, JSON.Marshal(struct) will encode "foo" as [102, 111, 111].

So I like the change, but I'd really like to see a test for it, since it
is one of those "everything seemed fine but failed in reality" issues.

https://codereview.appspot.com/7221070/