NBI v3 Method Stubs

This commit adds the methods stubs for the v3 NBI.
OVSDB can now meet the API freeze milestone while we work on the
implementation

Change-Id: Icdc78a64f31d4e62926284c4669ecec65877421a
Signed-off-by: Dave Tucker <djt@redhat.com>
Merge "NBI v3 Method Stubs"