Move static definition of forwarding.conf later in script

While the original implementation may have been to save the nameservers
given by the provider, we now just use a static nameserver.  As such we
can define the contents of forwarding.conf later and help avoid any
potential race conditions, such as that in bug 1373505.

Change-Id: I921cca03a6915f1e7b471d1bf90b82abcb1a0606
related-bug: 1373505
Merge "Move static definition of forwarding.conf later in script"