Improve power consumption and SLEEP mode :

- Disable IDLE hook (it would wake the device up as soon as possible).
 - Logger task sleep for 100ms (disable logging for better battery life)
 - Logging is disabled by default
 - Apply fix for ERRATA 87 (clear FPU interrupt before going to sleep). Ports files from FreeRTOS are now in the sources (they where in the SDK before)

src/Logging/NrfLogger.cpp

@@ -21,7 +21,7 @@ void NrfLogger::Process(void*) {
   NRF_LOG_INFO("Logger task started!");
   while (1) {
     NRF_LOG_FLUSH();
-    vTaskSuspend(nullptr);
+    vTaskDelay(100); // Not good for power consumption, it will wake up every 100ms...
   }
 }