Update unit tests to not actually make API calls

Currently the unit tests actually try to get the WSDL from api.softlayer.com, and try to make actual API calls during the tests.
To fix that we need to do the following:

1. Setup SoapClient to have a property for the Soap Client itself, which we can overload in the tests.
2. Have a fixture for the WSDL or something for the fake soap client to use.
