feature: add lxcfs enabled info to 'pouch info'

[zhuangqh]

Ⅰ. Describe what this PR did

This pr enhance the output of 'pouch info' by adding the info of lxcfs-enabled.

Ⅱ. Does this pull request fix one issue?

fixes #1137

Ⅲ. Describe how you did it

Ⅳ. Describe how to verify it

$ lxcfs /var/lib/lxcfs # launch lxcfs
$ pouchd --enable-lxcfs
$ pouch info
Containers: 0
 Running: 0
 Paused: 0
 Stopped: 0
Images:  0
ID: 
Name: vm
Server Version: 0.4.0-dev
Storage Driver: overlayfs
Driver Status: []
Logging Driver: 
Cgroup Driver: 
runc: <nil>
containerd: <nil>
Security Options: []
Kernel Version: 4.13.0-38-generic
Operating System: "Ubuntu 16.04.3 LTS"
OSType: linux
Architecture: 
HTTP Proxy: 
HTTPS Proxy: 
Registry: https://index.docker.io/v1/
Experimental: false
Debug: false
Labels:
  node_ip=192.168.199.128
  SN=Parallels-11
CPUs: 4
Total Memory: 3.847 GiB
Pouch Root Dir: /var/lib/pouch
LiveRestoreEnabled: false
LxcfsEnabled: true
Daemon Listen Addresses: [unix:///var/run/pouchd.sock]

Ⅴ. Special notes for reviews

[codecov-io]

Codecov Report

Merging #1152 into master will decrease coverage by 0.44%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #1152      +/-   ##
==========================================
- Coverage   16.03%   15.58%   -0.45%     
==========================================
  Files         173      173              
  Lines        9902     9821      -81     
==========================================
- Hits         1588     1531      -57     
+ Misses       8198     8180      -18     
+ Partials      116      110       -6

Impacted Files	Coverage Δ
cli/info.go	0% <0%> (ø)	⬆️
daemon/mgr/system.go	0% <0%> (ø)	⬆️
client/client.go	33.33% <0%> (-25.62%)	⬇️
pkg/kernel/kernel.go	72.72% <0%> (-6.23%)	⬇️
pkg/utils/utils.go	78.15% <0%> (-0.08%)	⬇️
cli/command.go	0% <0%> (ø)	⬆️
cli/cli.go	0% <0%> (ø)	⬆️
apis/opts/labels.go
apis/opts/intel_rdt.go
apis/opts/portbindings.go
... and 37 more

[allencloud]

LGTM