string Rest::buildParams(RequestData const &params) {
	if(params.empty()) {
		return "";
	}
	RequestData::const_iterator pb = params.begin(), pe = params.end();
	string data = pb->first+ "=" + pb->second;
	++ pb;
	if(pb == pe){
		return data;
	}
	for(; pb!= pe; ++ pb){
		data+= "&" + pb->first + "=" + pb->second;
	}

	return data;
}