[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.
With the huge work on Android by XBMC team and the fragmentation of the Android platform, logs are crucial but a lot of Android users including myself don't have easy access to the log file due to the need of root permissions to view/edit/copy it. This PR fixes this issue.
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.