Trailing equal sign in argument value

[WojciechLuczkow]

Fix for #85 was resolving problem of equal sign in the middle of value.

If one or more = signs are at the end of the value - they are all removed.

Following test case in src/clique_parser.erl will fail:

parse_valid_arg_value_with_trailing_equal_sign_test() ->
    Spec = spec(),
    ArgsAndFlags = ["client-id=anon-Base64v=="],
    {Spec, Args, Flags} = parse({Spec, ArgsAndFlags}),
    ?assertEqual(Args, [{"client-id", "anon-Base64v=="}]),
    ?assertEqual(Flags, []).

[WojciechLuczkow]

Changing string:token to string:split will fix the issue,

However string:split is available since OTP 20 which is not used in VerneMQ fork

Below I inserted workng replacement for parse_kv_args([Arg | Args], Acc)
It also removes hack for "equal" sign in middle of argument

parse_kv_args([Arg | Args], Acc) ->
    case string:split(Arg, "=") of
        [Key] ->
            {error, {invalid_kv_arg, Key}};
        [Key, []] ->
            {error, {invalid_kv_arg, Key}};
        [Key, Val] ->
            parse_kv_args(Args, [{Key, Val} | Acc])
    end.