mocks: extensions to the testServer
mocks: extensions to the testServer

- add capability to start the tests server with TLS enabled or disabled
- add capability to set responses for particular request paths

Change-Id: I82e8e2512a81e03f9dcb56e98fb2a8abe6df3e1e

vmware/photon-controller-go-sdk,vmware/photon-controller-go-sdk