Support reading since_epoch and secondary brightness files

TWFunc::Fixup_Time_On_Boot: Will now try to read
/sys/class/rtc/rtc0/since_epoch to correct time, if that fails
it will try to use the ats files to correct time.

TWFunc::Set_Brightness: One single function to set brightness
from both the automated functions and the gui actions. It is
able to set a second brightness path if present, it will set
them both the same value. Many Sony devices have 2 brightness
files in the sysfs that must be set to properly set the
brightness.

Change-Id: I7ca582109085dfbcb46b8de73ad031e4b7903fca

gui/action.cpp

@@ -824,6 +824,11 @@ int GUIAction::doAction(Action action, int isThreaded /* = 0 */)
 		return 0;
 	}
 
+	if (function == "setbrightness")
+	{
+		return TWFunc::Set_Brightness(arg);
+	}
+
 	if (isThreaded)
 	{
 		if (function == "fileexists")