bugfix: Volume info of inspect output is incompatible with Moby API

[HusterWan]

Signed-off-by: Michael Wan [email protected]

Ⅰ. Describe what this PR did

#./docker -H unix:///run/pouchd.sock inspect eff3a2846686
[]
json: cannot unmarshal string into Go value of type struct {}

Ⅱ. Does this pull request fix one issue?

fixes #1211

Ⅲ. Describe how you did it

Ⅳ. Describe how to verify it

root@osboxes:test (zr/fix-volume-struct *) -> docker -H unix:///run/pouchd.sock inspect test2
[
    {
        "Args": null,
        "Config": {
            "Cmd": [
                "/bin/bash"
            ],
            "Entrypoint": null,
            "Env": [
                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
            ],
            "Hostname": "osboxes",
            "Image": "registry.hub.docker.com/library/ubuntu:14.04",
            "OnBuild": null,
            "Shell": null,
            "Volumes": {
                "/mnt": null
            }
        },
        "Created": "2018-04-25T11:50:50.324220921Z",
        "GraphDriver": {

Ⅴ. Special notes for reviews

[rudyfly]

change to volumeSlice to volumeSet？

[codecov-io]

Codecov Report

Merging #1213 into master will decrease coverage by 0.05%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #1213      +/-   ##
==========================================
- Coverage    15.7%   15.64%   -0.06%     
==========================================
  Files         171      171              
  Lines       10398    10403       +5     
==========================================
- Hits         1633     1628       -5     
- Misses       8645     8655      +10     
  Partials      120      120

Impacted Files	Coverage Δ
daemon/mgr/container.go	0% <0%> (ø)	⬆️
pkg/bytefmt/bytefmt.go	88.88% <0%> (-0.95%)	⬇️

[rudyfly]

LGTM