lxd/networks: Detect unknown network type in networksPost, dont assume bridge
lxd/networks: Detect unknown network type in networksPost, dont assume bridge

When network type is not supplied, defaults to bridge to maintain compat with older clients.

Signed-off-by: Thomas Parrott <6b778ce645fb0e3dde76d79eccad490955b1ae74@canonical.com>

mjeanson/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,hallyn/lxd,atxwebs/lxd,stgraber/lxd,mjeanson/lxd,Skarlso/lxd,hallyn/lxd,lxc/lxd,atxwebs/lxd,Skarlso/lxd,stgraber/lxd,Skarlso/lxd,atxwebs/lxd,lxc/lxd,Skarlso/lxd,lxc/lxd,hallyn/lxd,hallyn/lxd,atxwebs/lxd,lxc/lxd,lxc/lxd,mjeanson/lxd,lxc/lxd,hallyn/lxd,stgraber/lxd,hallyn/lxd,stgraber/lxd,stgraber/lxd