errors: add configuration exception

The configuration exception will be thrown for configuration errors.

Change-Id: Ibf9e220826ede46a5de748e73aa328300ed01f79
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/errors/exception.hpp b/errors/exception.hpp
index c1c789a..cc1bd07 100644
--- a/errors/exception.hpp
+++ b/errors/exception.hpp
@@ -34,3 +34,19 @@
   private:
     std::string message;
 };
+
+class ConfigurationException : public std::exception
+{
+  public:
+    ConfigurationException(const std::string& message) : message(message)
+    {
+    }
+
+    virtual const char* what() const noexcept override
+    {
+        return message.c_str();
+    }
+
+  private:
+    std::string message;
+};