Splunk Log Store may return an empty result set if the time zones are not the same

## Environment details:

* local deployment, vagrant, native ubuntu, Mac OS, Bluemix, ...
* version of docker, vagrant, ubuntu, ...

## Steps to reproduce the issue:

1. Set the logging spi to splunk: `CONFIG_whisk_spi_LogStoreProvider=whisk.core.containerpool.logging.SplunkLogStoreProvider`
2. Ensure the splunk user used for querying and the controller have different time zones
3. Check the controller logs:

## Provide the expected results and outputs:

```
{"error":"Object is missing required member 'results'","code":"P4VoKRECg6iECBf0SGILQm7G5rqZMNma"}
```

## Provide the actual results and outputs:

No error and you should get the logs back.