Automatic merge from submit-queue (batch tested with PRs 49870, 49416, 49872, 49892, 49908)

Make "kubeadm version" json format output more readable.

**What this PR does / why we need it**:
Add indent to json format output.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
ref: #43750 #46598

**Special notes for your reviewer**:
output example:
```
#kubeadm version -o json
{
  "clientVersion": {
    "major": "1",
    "minor": "8+",
    "gitVersion": "v1.8.0-alpha.2.1026+d8205661-dirty",
    "gitCommit": "d8205661",
    "gitTreeState": "dirty",
    "buildDate": "2017-07-31T12:14:28Z",
    "goVersion": "go1.8.3",
    "compiler": "gc",
    "platform": "linux/amd64"
  }
}
```


**Release note**:

```release-note
NONE
```