packages: Coding style

Adding return in the first if is a little bit easier to read than a big
else
ceph: Fixing apt-key

The apt-key shall be part of the chroot command
base.insall: Using closest mirror for all repo

As per commit d1139932594f29b486012424535503e388c39998, let's use the
closest repository for all component we need to setup.
Remove alien package
test target depends on mysql.done

The dependency is defined in kvm-test.configure:

    set_role('mysql', 'D7-F.1.0.0', disk1)
doc: list required packages on Debian
doc: add a not about root privilege
avoid a chmod warning about missing *.hw file
doc: explains how to ignore config/*.cmdb changes