Update lxc_template.go

If networking is disabled, but then pipework is used later to add nics, the network still doesn't function. Using flags=up for empty networking fixes this.
Docker-DCO-1.1-Signed-off-by: James DeFelice <james.defelice@ishisystems.com> (github: jdef)

execdriver/lxc/lxc_template.go

@@ -15,6 +15,7 @@ lxc.network.name = eth0
 {{else}}
 # network is disabled (-n=false)
 lxc.network.type = empty
+lxc.network.flags = up
 {{end}}
 
 # root filesystem