minor fixes

session_manager.cpp

@@ -40,7 +40,7 @@ int session_manager::install_command(std::string package){
     }
   std::string buffer;
   this->con->read_string(buffer,2);
-  return atoi(buffer.data());
+  return (buffer=="ok")?1:-1;
 }
 
 int session_manager::remove_command(std::string package){