Add debug mode

Description:
    1. Could enable debug mode by adding file: /etc/thermal.d/debugging.
        $ mkdir /etc/thermal.d
        $ touch /etc/thermal.d/debugging
        $ systemctl restart phosphor-pid-control

    2. Could record fans output PWM, chosen temperature, PID/stepwise output PWM in debug mode.

Design:
    1. Create debugging file and restart service to enable debug mode.

    2. Check if debug mode is enabled to output fans output PWM, chosen temperature,
       PID/stepwise output PWM, and so on.

Test Case:
    1. Enable debug mode and check logs: pass

Change-Id: I8527ebcb81e723298ba7e786b4501f986ebd439e
Signed-off-by: Bonnie Lo <Bonnie_Lo@wiwynn.com>
diff --git a/test/zone_mock.hpp b/test/zone_mock.hpp
index 9c80a50..b63408f 100644
--- a/test/zone_mock.hpp
+++ b/test/zone_mock.hpp
@@ -35,6 +35,7 @@
     MOCK_CONST_METHOD0(getManualMode, bool());
     MOCK_CONST_METHOD0(getFailSafeMode, bool());
     MOCK_CONST_METHOD0(getFailSafePercent, double());
+    MOCK_CONST_METHOD0(getZoneID, int64_t());
 
     MOCK_CONST_METHOD0(getCycleIntervalTime, uint64_t());
     MOCK_CONST_METHOD0(getUpdateThermalsCycle, uint64_t());