Improvement on run.NewServer related to meta.QueryAuthorizer.

[chris-ramon]

Details:

• Commit: e3b4b71 introduced the type meta.QueryAuthorizer which is a field of httpd.Handler and is used on httpd/handler.go to validate authorization, like so:

if h.requireAuthentication {
    if err := h.QueryAuthorizer.AuthorizeQuery(user, query, db); err != nil {
        if err, ok := err.(meta.ErrAuthorize); ok {
            h.Logger.Printf("unauthorized request | user: %q | query: %q | database %q\n", err.User, err.Query.String(), err.Database)
        }
        httpError(w, "error authorizing query: "+err.Error(), pretty, http.StatusUnauthorized)
        return
    }
}

• When run.NewServer wires all the services; and it creates new instance of httpd.Service, it does not set *Handler.QueryAuthorizer (due some reason I might be missing? cc/ @benbjohnson) - due this, performing http requests against run.Server will throw a run time error: invalid memory address or nil pointer dereference, because *Handler.QueryAuthorizer is nil.
• This PR updates run.Server.appendHTTPDService to set that missing QueryAuthorizer explained above.
• CHANGELOG.md updated
• Rebased/mergable
• Tests pass
• Sign CLA

[jwilder]

👍 Thanks @chris-ramon!