fixes #777 - this enable auditing of when a host is changing its puppet class assignmetns

one limitation of this patch is that at the moment, each class change
gets its own audit record.

fixes #1001, foreman should not use dhcp next server when tftp is not used

Fixes #1000 Out of sync shows hosts with last report equal puppet_interval

fixes #1031 - Adds a CentOS logo

Fixes #1026 - Medium create fails with 'invalid nfs path'

Signed-off-by: Paul Kelly <paul.ian.kelly@googlemail.com>

fixes #1029 - allows smart variables to be resolved via http get request.

this would allow to an external query to resolve a variable value to a given host.

e.g.
http://foreman/hosts/&lt;fqdn&gt;/lookup_values/&lt;variable_name>

fixes #322 Ability to add custom variables and multiple values resovled
in a dynamic Hierarchally order

This commits introduces the ability to define variables per puppet
class.

additionally, each class can have multiple values, depends on the host
which is requesting that variable....

splitted setting default data from the migration
this allows to add new data and modify its defaults
improved settings UI a bit more
refs #100

Fixes #1020 - edit multiple ok button

Signed-off-by: Paul Kelly <paul.ian.kelly@googlemail.com>

Fixes #1013 - Architecture change is ignored on the new hostgroup page

Signed-off-by: Paul Kelly <paul.ian.kelly@googlemail.com>