Fix for Issue #17: allEntries on schemas with new lines (JSON-ified)

Integrated google-gson for more reliable serialization over the wire.
Added tests for JSON.
Client tests now submitted to persistence/multi-line tests.
Having a separate method per media type doesn't look nice. Is it not possible to have a single method which can look at `Accept` header and respond with appropriate `Content-Type`? (That logic can be centralized). Granted, this won't be able to take advantage of annotations, but IMHO it would be cleaner to have one method per resource with common media type logic than to have method per resource per media type.