Fixes #259 - Registers a node prior to performing dependant tests

This PR enables several tests in the /node endpoint which were disabled.  The /node/register test is performed first to add a node to the database.  A new test was added for /node/checkin using the UUID from the register test.  The GET node by uuid test was enabled and uses the UUID from the register test.

Implements POST /node/register test
Implements GET /node/checkin test
Enables GET /node/{uuid} test
Fixes #259