Fix out of memory crash

Scale all bitmaps to the same size to avoid problems with
extraordinarily large icons.
Credits to Daniel (github user DaPa: https://github.com/DaPa)
(https://github.com/jensstein/oandbackup/issues/73)
Close BufferedReader

Avoid potential resource leak.
Credits to Daniel (github user DaPa: https://github.com/DaPa)
(https://github.com/jensstein/oandbackup/issues/73)
Add busybox prefix to sed and awk

Credits to Daniel (github user DaPa: https://github.com/DaPa)
(https://github.com/jensstein/oandbackup/issues/73)