Initial work on listing rels for a node via kernel API.

 o Simply adds the relevant methods to the Statement API and
   introduces a temporary bridge implementation in LegacyKernelOperations.
 o Remaining: Use implementation in surface APIs
 o Remaining: Move relevant NodeImpl/NodeManager code into kernel.
CoreAPI getRelationships now delegates to kernel API.

 o getRelationships in NodeProxy now uses the KernelAPI
 o getSingleRelationship in NodeProxy uses Kernel API
 o hasRelationships in NodeProxy uses the Kernel API
 o Remaining: Move NodeImpl & NodeManager code into kernel.
Merge pull request #1815 from jakewins/kernel-list-rels

Initial work on listing rels for a node via kernel API.