Lock network facts unless specified

Due to a new upstream change in vswitch, ip addresses
for interfaces are now moved to bridges, which can confuse
facter's ipaddress facts. This change will lock the facts
to their initial value on the first run of the bootstrap
script, preventing issues arising from puppet referring to
facts that no longer exist (eg for the external interface)

Change-Id: I10c67c4d2b06f8438f3d3bf05b45f647de6449a7
Merge "Lock network facts unless specified"