include: add missing headers

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I6b26a1bea2aae173b57dbd8affa0ba4991b1c9bb
diff --git a/include/Thresholds.hpp b/include/Thresholds.hpp
index f1e7cc6..00df68c 100644
--- a/include/Thresholds.hpp
+++ b/include/Thresholds.hpp
@@ -2,7 +2,12 @@
 #include "Utils.hpp"
 
 #include <boost/asio/io_service.hpp>
+#include <list>
+#include <memory>
 #include <nlohmann/json.hpp>
+#include <string>
+#include <utility>
+#include <vector>
 
 struct Sensor;
 namespace thresholds