Добавлены структуры исключений

src/exceptions/exception400_bad_request.cpp

@@ -0,0 +1,18 @@
+#include "exception400_bad_request.h"
+
+#include <boost/beast/core/error.hpp>
+
+using namespace std;
+using namespace std::literals;
+
+namespace uad
+{
+exception400_bad_request::exception400_bad_request(const string& info): message_(info)
+{
+}
+
+char const* exception400_bad_request::what() const
+{
+  return message_.c_str();
+}
+}