Adding capability to specify sdk version / device variation via Webtest ...

Addressing ticket #53. Adding capabilities to allow a use to specify sdk / device variation
Do we really need to use `StringUtils.contains` and `StringUtils.split` ? Can we not just use `device.contains` and `device.split` here ? I believe `StringUtils` basically shields you for null values, but if that were the case then the parent if condition itself would be throwing a `NullPointerException` because we have not shielded the code there.