base: lldpad for every role

This patch is about adding lldp detection for every role. This is not
really pxe specific as it could be very useful for every single role
being able to grab or set some LLDP information.
pxe & health: ethtool & hdparm are already in base

No need to add here some packages that are already installed in base.
Make the code smaller & easier to read.
init: Adding respawn

As per issue #138, it would be very useful being able to restart the
deploiement process without rebooting.

The required steps to make it done properly:
- umounting filesystems
- killing some process
- removing temporary files

The temporary files are targetting log files but also files generated
during the boot process like those coming from detect.py, the configure
script or some files generated by /vars

The process to be killed are those locking the filesystems like udev,
dhclient etc..

The filesystem to be umounted are those from /chroot and all virtual
filesystem like /proc,/sys,/run. /dev could not be umounted as we run
respawn from a pts/ which locks /dev/pts/.

To trigger a respawn, just call /respawn
init: Replace fatal_error by give_up

if the detection fails, we were in a situation were we called a
non-existing function. It should have been give_up() instead of
fatal_error()
init: Don't remount /dev if already mounted

When respawing the installation process, the /dev was remounted again
(as we cannot umount it due to chicken & egg issue) over the existing
/dev.

As a result, we were not able to get new ptys making the whole process
failing.

This patch insure not remounting /dev/ if already mounted.
respawn: Don't hide final console on the system

Let's redirect log directly to /log instead of redirecting everything to
/log preventing from keeping a live console.
respawn: Fixing style
base: Add selinux targeted policies packages