This patch proposes a new element which installs fail2ban on the final
image. More crucially, a custom jail.local is injected during built
time which is a useful feature for cloud admins.
Change-Id: I47b90bbf3809cd6f90148b848b2afe4233be79d7
Signed-off-by: Charalampos Kominos <hkominos@gmail.com>