Changed the console blank timeout

The screen blanks after a predefined timeout (during installation).
This change sets that timeout to 60 minutes, buy which time the
installation should hopefully be finished.
it's the same as

    setterm -blank 60

because setterm isn't compiled into the busybox binary, I tried to figure out how setterm accomplishes the screen blanking and found [this](http://code.metager.de/source/xref/linux/utils/util-linux/term-utils/setterm.c#736) :grin: 

it's just an ANSI escape code / sequence, documented in the [Linux Programmer's Manual (console_codes)](http://man7.org/linux/man-pages/man4/console_codes.4.html) (search for screen blank timeout)