Fixed an unclosed stream in BluetoothObserver
Redesigned handling of internal/external paths to cope with SD card removal

Also fixed an activity leak on first install and handled an out of
memory error on first panorama image load
Removed unnecessary string format (potential locale issues)
Fixed two lint minor warnings
Use inbuilt getString to format string resources (rather than String.format)
Use Locale.ENGLISH for export filename formatting
Don't hide the media controller on resume if it was paused