Move to GinkGo framework

[aufi]

Based on discussion with QE colleagues, we agreed that this repo is going to use ginkgo test framework. The tackle2-hub repo API will stay with go test, but its packages like binding.RichClient or api.* will be re-used here.

Let's track the switching to ginkgo in this issue.

Definiton of Done: all tests in go-konveyor-tests repo use ginkgo (and no one go test directly).

For visibility @mguetta1 @sshveta

[aufi]

First ginkgo tests: #16