Delete VM pings the agent before stopping, optionally timing out

- Refactor lifecycle tests to 'bosh-micro delete' after each test
- Refactor lifecycle tests into multiple tests to make debugging easier
- Add Instance & InstanceManager
- Refactor DeleteCmd to use InstanceManager.FindCurrent & Instance.Delete
- Added cmd factory dependency getters w/ caching
- Refactor Deployer to use Instance.DeleteAll & InstanceManager.Create
- Move DeleteUnused from Deployer to StemcellManager
- Rename VM.WaitToBeReady to WaitUntilReady to be consistent with other wait method names

[#83884280]

Signed-off-by: Karl Isenberg <kisenberg@pivotal.io>
Add acceptance tests for deploying/deleting with unresponsive agent

[#83884280]

Signed-off-by: Karl Isenberg <kisenberg@pivotal.io>
Move DeleteUnused from DiskDeployer to DiskManager

[#84154662]

Signed-off-by: Karl Isenberg <kisenberg@pivotal.io>