Part one of stubbing the fog interface

I cannot figure out one thing - pushing it for Sneha to take a look. All tests still pass (though I have commented out the two logger lines where my problem is).
This is how you mock an object in the test

In fact the name is only required for a log message and had to be mocked in an entirely different way - this I think is more support for the argument that fog interface should be consistent about what it returns, but that's a different story.
Have spec_helper require stub_fog_interface

To save putting it in all test files.
These tests no longer need to be commented out
Use stub fog interface in vm spec as well

At the moment this doesn't make a great deal of difference to this test because the test is set up with the vm and vapp mocked as well. Ideally the stub fog interface would work as per the fog interface and return these mocks as well.
Merge pull request #23 from alphagov/stub-fog-interface

Stub fog interface