feature: add volume list command

[rudyfly]

1.Describe what this PR did
Add volume list command, it returns all the volumes in pouch.
Now it just returns the name of volume.

2.Does this pull request fix one issue?

NONE

3.Describe how you did it

4.Describe how to verify it
create three volume in pouchd

# pouch volume create -d local -n pouch-volume-1 -o size=100g
CreatedAt:
Driver:       local
Mountpoint:
Name:         pouch-volume-1
Scope:
# pouch volume create -d local -n pouch-volume-2 -o size=100g
Driver:       local
Mountpoint:
Name:         pouch-volume-2
Scope:
CreatedAt:
# pouch volume create -d local -n pouch-volume-3 -o size=100g
Scope:
CreatedAt:
Driver:       local
Mountpoint:
Name:         pouch-volume-3

then use list to get the volumes that are created just now.

# pouch volume list
Name:
pouch-volume-1
pouch-volume-2
pouch-volume-3

5.Special notes for reviews

Signed-off-by: Rudy Zhang rudyflyzhang@gmail.com

[codecov-io]

Codecov Report

Merging #578 into master will decrease coverage by 0.14%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master     #578      +/-   ##
==========================================
- Coverage   13.58%   13.43%   -0.15%     
==========================================
  Files          65       65              
  Lines        3541     3579      +38     
==========================================
  Hits          481      481              
- Misses       3010     3048      +38     
  Partials       50       50

Impacted Files	Coverage Δ
client/volume.go	0% <0%> (ø)	⬆️
cli/volume.go	0% <0%> (ø)	⬆️

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[allencloud]

Could you add some integration test including API test case and cli test case? @rudyfly

[rudyfly]

@allencloud @Letty5411 How to add integration test，can you give me an example？

[allencloud]

Yes, you can take a look at file test/api_volume_create_test.go and test/cli_volume_test.go.

The previous one is focused on API integration test and the latter one is cli integration test. @rudyfly

[rudyfly]

@allencloud @Letty5411 PTAL.

[allencloud]

LGTM, while I would like to invite @Letty5411 to double check this.

[Letty5411]

LGTM