apt-dater-host for Alpine

I use apt-dater to manage updates to numerous XEN domUs, after starting to use Alpine Linux I needed to implement apt-dater-host support for Alpine Linux.

Normally apt-dater host support is implemented in Perl, but as that is not present in a base Alpine install, this implementation of ADP-0.6 was done in ash, sed and awk provided by Busybox.

Link to code on GitHub: apt-dater-host apk support (merged upstream).

Example output, when running apt-dater against an alpine host with pending updates

v [-] 192.168.3.8 (alpine 3.4.0 ; 4.4.11-0-grsec)
       u: alpine-base
       u: alpine-baselayout
       u: alpine-conf
       u: blkid
       u: busybox
       u: busybox-initscripts
       u: busybox-suid
       u: curl
       u: expat
       u: libblkid
       u: libcrypto1.0
       u: libssl1.0
       u: libuuid
       u: linux-grsec
       u: mkinitfs
       u: musl
       u: musl-utils