Add upstream dnsmasq resolvers to dnsmasq.conf

This will allow tenants who do not specify a
DNS server in their subnet creation to add
servers for the default dnsmasq process to use
to resolve upstream

Change-Id: I99f54667b758f83d8821b97957de92b97687740c
Add dhcp_domain option to dhcp_agent.ini

This will allow you to set the domain dnsmasq hands out
to instances.
From: http://docs.openstack.org/trunk/openstack-network/admin/content/dhcp_agent_ini.html
dhcp_domain=openstacklocal  (StrOpt) Domain to use for building the host names.

Defaults to "openstacklocal"

Change-Id: Id963b7a6eeb7d57a5a0797d4e1e2981b8fd9e7a1
Don't use OpenDNS as the default resolvers

OpenDNS returns self referencing records instead of pure
NXDOMAIN records:

root@kevin-test-1:~# host kevin-test
kevin-test has address 67.215.65.132
Host kevin-test not found: 3(NXDOMAIN)

NetRange:       67.215.64.0 - 67.215.95.255
CIDR:           67.215.64.0/19
OriginAS:       AS36692
NetName:        OPENDNS-NET-3

Clearly this is not preferable when the server is being
used as an upstream resolver for internal DNS which may
send incorrectly configured applications running in VMs
to the wrong place

Change-Id: I098bb57e9e71fc3db5b3e4b3d42d9a3e1d966a04