REST client library should be compatible with both ModeShape 2.x and 3.x REST services

The REST client library should be able to talk to older versions of the ModeShape REST service.

In 3.0 we added a new REST API, and moved the older REST API to "v1/" resources. However, the 3.0 REST client still uses only the older-style API, and so the resources that it uses must change if it's talking to a 3.x REST service vs a 2.x REST service.