Fix: raise the right exception on failed to connect to server

src/main/java/com/sheepit/client/Server.java

@@ -482,6 +482,9 @@ public class Server extends Thread {
 			this.lastRequestTime = new Date().getTime();
 			return response;
 		}
+		catch (ConnectException e) {
+			throw new ConnectException("Unexpected response from HTTP Stack" + e.getMessage());
+		}
 		catch (IOException e) {
 			throw new IOException("Unexpected response from HTTP Stack" + e.getMessage());
 		}