MODE-2218 Corrected the REST client's methods that obtain the node types from recent servers

The structure of the node types (under `/jcr:system/jcr:nodeTypes`) changed quite some releases ago (not exactly sure when), and the JDBC Driver (and REST client) could no longer read the node types' property definitions and child node definitions. The REST client's methods that obtain the node type representations from the server were updated to also handle the newer format as well as keep support for the old format.

There are new/updated test cases that verify the REST client can correctly obtain the node types from the old representation and the new representation.

The resulting client JAR was then used in Designer (latest version) to import via JDBC from a ModeShape 3.8.0.Final server and a ModeShape 4.0.0.Alpha3 server.