* Reduce SONiC image filesystem size
Add a build option to reduce the image size.
The image reduction process is affecting the builds in 2 ways:
- change some packages that are installed in the rootfs
- apply a rootfs reduction script
The script itself will perform a few steps:
- remove file duplication by leveraging hardlinks
- under /usr/share/sonic since the symlinks under the device folder are lost during the build.
- under /var/lib/docker since the files there will only be mounted ro
- remove some extra files (man, docs, licenses, ...)
- some image specific space reduction (only for aboot images currently)
The script can later be improved but for now it's reducing the rootfs
size by ~30%.
* restore fully featured vim package
