fixes #786 - Add the option to use existing DHCP reservations

note that this patch only ensures that the ip used is the same as the
existing dhcp record.
if there is a mistmatch in what foreman expects in the reservation vs.
actual state, #944 should kick in.

fixes #1313 ensure all host names are lowercased

Signed-off-by: Florian Koch <florian.koch1981@googlemail.com>

fixes #1432 - subnet gateway infos only saved when fill gateway and dns fields

the informations in the subnet form only saved if you fill the gateway and one dns fields
  the cause is the validation in models/subnets.rb

whyever the :allow_blank should work, but i need to add :allow_nil also to get this working...

fixes #1434 - Status page is broken

fixes #1361 -- Add gateway and dns fields to Subnets

• Allow subnet values to be accessed in provisioning templates

fixes #1176 - SLES still did not display correct minor version

fixes #1426 - Foreman should not fail if dns domain has no SOA or NS records

fixes #1423 - Hardware model field should be mandatory when selecting Sparc architecture

fixes #1422 - Media is greyed out when creating Solaris hosts

fixes #1421 - expose subnet ranges for automatic IP address allocations