Remove unnecessary setting of user id to constant value.
Use predefined conference id constants.
Return correct Location header registrations URI from create registration endpoint.
Use JsonNodeHelper to serialize json node.
Remove JsonUtils in favor of JsonNodeHelper.
Refactor by moving 'block' package to web api model package and renaming package to 'answer' (since the Question objects are populated from registration answers)
Use JsonNodeHelper to deserialize json.
Eliminate Gson in favor or Jackson for JSON serialization/deserialization.
Encapsulate in JsonNodeHelper.