Unit Test - cmd package

Determine a list of go files and functions in those files for which we can write unit tests, create one test file per go file

Go files under [cmd](https://github.com/apache/incubator-openwhisk-wskdeploy/tree/master/cmd) package:

```
add.go
init.go
publish.go
report.go
root.go
undeploy.go
version.go
```