wsk property get does not work if api host is not set

@rabbah commented on [Sun Jun 11 2017](https://github.com/apache/incubator-openwhisk/issues/2358)

```
> WSK_CONFIG_FILE= wsk property get --all
error: The API host is not valid: An API host must be provided.
Run 'wsk --help' for usage.
```

If I'm trying to get all the properties, I think the CLI should just show what is set and what isn't.

Trying to override this:

```
> WSK_CONFIG_FILE= wsk property get --all --apihost xxx
whisk auth
whisk API host
whisk API version v1
whisk namespace _
whisk CLI version 2017-06-09T21:18:47+00:00
whisk API build Unknown
whisk API build number Unknown
error: Unable to obtain API build information: Get openwhisk.ng.bluemix.net/v1: unsupported protocol scheme ""
```

Seems to show there's a baked in reference to bluemix somewhere: https://github.com/apache/incubator-openwhisk/blob/master/tools/cli/go-whisk/whisk/client.go#L36 which should not be present, and looks like a bug since the default does not seem to hold if that was intended.