openstack-full: Use Debian meta-packages for linux-{headers,image}

Debian build is broken due to an NMU on Linux kernel,headers; This
commit update packages names, using meta-packages in order to avoid
potential future issues.

* linux-headers-3.16-0.bpo.3-amd64 →  linux-headers-3.16.0-0.bpo.4-amd64
* linux-image-3.16-0.bpo.3-amd64 → linux-image-3.16.0-0.bpo.4-amd64

Note: This fixes the build issue on Debian.

 :bangbang: **Question** We pin-point the Kernel version in order to avoid unattended updates?