Fix 414 Request-URI Too Large

We occurs 414 sometimes when we creates freee's deals.
Because, OAuth2 combined endpoint url and `params` option string.

see. https://github.com/intridea/oauth2/blob/ebe4be038ec14b3496827d29cb224235e1c9f468/lib/oauth2/client.rb#L85

I think we should not use `params` option.