Mount /dev/shm as a tmpfs.

Fixes #1122.

lxc_template.go

@@ -76,7 +76,7 @@ lxc.mount.entry = sysfs {{$ROOTFS}}/sys sysfs nosuid,nodev,noexec 0 0
 lxc.mount.entry = devpts {{$ROOTFS}}/dev/pts devpts newinstance,ptmxmode=0666,nosuid,noexec 0 0
 #lxc.mount.entry = varrun {{$ROOTFS}}/var/run tmpfs mode=755,size=4096k,nosuid,nodev,noexec 0 0
 #lxc.mount.entry = varlock {{$ROOTFS}}/var/lock tmpfs size=1024k,nosuid,nodev,noexec 0 0
-#lxc.mount.entry = shm {{$ROOTFS}}/dev/shm tmpfs size=65536k,nosuid,nodev,noexec 0 0
+lxc.mount.entry = shm {{$ROOTFS}}/dev/shm tmpfs size=65536k,nosuid,nodev,noexec 0 0
 
 # Inject docker-init
 lxc.mount.entry = {{.SysInitPath}} {{$ROOTFS}}/sbin/init none bind,ro 0 0