nano: move to system
busybox: add 'crond' and 'crontab' applets
add cron support
remove package: dcron
busybox: move crond init script to scripts folder, cleanups

Signed-off-by: Stephan Raue <stephan@openelec.tv>
xbmc: do not depend on 'bc'
remove package: 'bc'
Merge branch 'master' of github.com:OpenELEC/OpenELEC.tv into openelec-next