Remove the authority
This function removes the authority, which includes the userinfo, host, and a port if present.
assert( url( "http://example.com/echo.cgi" ).remove_authority().buffer() == "http:/echo.cgi" );
this->has_authority() == false && this->has_userinfo() == false && this->has_port() == false
authority = [ userinfo "@" ] host [ ":" port ]
userinfo = *( unreserved / pct-encoded / sub-delims / ":" )
host = IP-literal / IPv4address / reg-name
port = *DIGIT