[ANDROID] Store the log file in a user-accessible location

xbmc.log on Android is stored in /data/data/org.xbmc.xbmc/ which can only be accessed with root permissions. This patch changes the log path to:
/sdcard/Android/data/org.xbmc.xbmc/files/.xbmc/userdata/ which is accessible by all file managers and ftp servers with no root privileges needed.