add hackney_url:make_url/3, hackney_url:qs/1, hackney_url:parse_qs/1

- construct an url with hackney_url:make_url/3

1> hackney_url:make_url(<<"https://friendpaste.com">>,
<<"/_all_languages">>, [{<<"token">>, <<"xxxx">>}]).
"https://friendpaste.com//_all_languages?token=xxxx"\

- encode a query or a form using hackney_url:qs/1
- parse a query or a form using hackney_url:parse_qs/1

The hackney_form is kept around for now to keep the compatibility with
old codes.