Implement heartbeat for uptime monitoring

You can now monitor the bot's uptime via any external tool that supports push heartbeats. The bots sends a GET request every 30 seconds to show that it's online. The URL is hardcoded for the moment, but very easy to change.

src/main/java/wtf/beatrice/hidekobot/runnables/HeartBeatTask.java

@@ -0,0 +1,53 @@
+package wtf.beatrice.hidekobot.runnables;
+
+import wtf.beatrice.hidekobot.Configuration;
+import wtf.beatrice.hidekobot.utils.Logger;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.URL;
+
+public class HeartBeatTask implements Runnable
+{
+    private final Logger logger;
+
+    public HeartBeatTask()
+    {
+        logger = new Logger(getClass());
+    }
+
+
+
+    @Override
+    public void run()
+    {
+        String apiKey = Configuration.getHeartBeatApiKey();
+        if(apiKey == null || apiKey.isEmpty()) return;
+
+        String urlString = Configuration.getFullHeartBeatLink();
+        try {
+
+            URL heartbeatUrl = new URL(urlString);
+
+            HttpURLConnection connection = (HttpURLConnection) heartbeatUrl.openConnection();
+            connection.setRequestMethod("GET");
+            connection.setConnectTimeout(5000);
+            connection.setReadTimeout(5000);
+
+            int responseCode = connection.getResponseCode();
+            if(200 <= responseCode && responseCode < 300)
+            {
+                // only log ok response codes when verbosity is enabled
+                if(Configuration.isVerbose()) logger.log("Heartbeat response code: " + responseCode);
+            }
+            else
+            {
+                logger.log("Heartbeat returned problematic response code: " + responseCode);
+            }
+
+        } catch (IOException e) {
+            logger.log("Error while trying to push heartbeat: " + e.getMessage());
+        }
+
+    }
+}