Revert "Revert recent commits to fix CI"

This reverts commit 28c1c33b4294c2cdab079e70e3d119f62a0fc993.
Refactor space summary controller.

- move logic from controller into SpaceSummarizer object.
- simplify tests

Signed-off-by: Momchil Atanasov <m.momchil@gmail.com>
Refactor stubbed instances_reporter expectations

- the actual app instance may be different, validate the expected guid is
  requested

Signed-off-by: Momchil Atanasov <m.momchil@gmail.com>
Expose instance information from diego.

- add a diego_instances_reporter
- inject a factory that chooses between legacy_instances_reporter and
  diego_instances_reporter based on the app
- test cleanup to use satisfy {} matcher for argument validation on stubs

Signed-off-by: Momchil Atanasov <m.momchil@gmail.com>