manager: use ring::to_string

Using std::to_string is not possible on Android

Change-Id: I32ccd3e6ef7a56f7a805c00f5c3de749388cf8ce
Tuleap: #671

src/manager.cpp

@@ -2443,12 +2443,12 @@ Manager::testAccountICEInitialization(const std::string& accountID)
 
     if (ice->waitForInitialization(ICE_INIT_TIMEOUT) <= 0)
     {
-        result["STATUS"] = std::to_string((int) DRing::Account::testAccountICEInitializationStatus::FAILURE);
+        result["STATUS"] = ring::to_string((int) DRing::Account::testAccountICEInitializationStatus::FAILURE);
         result["MESSAGE"] = ice->getLastErrMsg();
     }
     else
     {
-        result["STATUS"] = std::to_string((int) DRing::Account::testAccountICEInitializationStatus::SUCCESS);
+        result["STATUS"] = ring::to_string((int) DRing::Account::testAccountICEInitializationStatus::SUCCESS);
         result["MESSAGE"] = "";
     }