完成http相关接口

src/Http/HttpClient.h

@@ -233,12 +233,15 @@ public:
     void setBody(const HttpBody::Ptr &body){
         _body = body;
     }
-    const string &responseStatus(){
+    const string &responseStatus() const{
         return _parser.Url();
     }
-    const HttpHeader &responseHeader(){
+    const HttpHeader &responseHeader() const{
         return _parser.getValues();
     }
+    const Parser& response() const{
+        return _parser;
+    }
 protected:
     /**
      * 收到http回复头