AppObserver can instruct diego to stop an app when the app is deleted

Signed-off-by: Amit Gupta <agupta@pivotallabs.com>
Rename json_match to match_json, and json to actual
whitespace
Add match_object matcher for pretty output when deeply nested JSON/YAML-like objects aren't equal
Add interal endpoint for bulk fetching of started apps, for DIEGO
Clean up API documentation for Service endpoints

[#73431654]

Signed-off-by: Joseph Palermo <jpalermo@pivotallabs.com>