Use switchblade for integration testing

[thitch97]

"Switchblade is an integration testing framework for Cloud Foundry v2b buildpacks. It enables test authors to write tests once, and then run them either against a real Cloud Foundry, or their local Docker daemon."

Using switchblade in our integration testing should greatly improve the ability to rapidly iterate during buildpack development.

Blocked by #432

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this:

https://www.pivotaltracker.com/story/show/179436866

The labels on this github issue will be updated when the story is started.

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this:

https://www.pivotaltracker.com/story/show/179452762

The labels on this github issue will be updated when the story is started.