This patch adds the VolumeConnector object. It handles the
volume connector information that is stored in the database.
Co-Authored-By: Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>
Co-Authored-By: Stephane Miller <stephane@alum.mit.edu>
Co-Authored-By: Ruby Loo <ruby.loo@intel.com>
Change-Id: I06aa1a94401e7c7faeb019926272a072d1ed1c51
Partial-Bug: 1526231