Emit an interfaces added signal
Emit an interfaces added signal

Resolves openbmc/openbmc#1710

Change-Id: Ibbda0fa52de6a569418db939f6527ff985e869e9
Signed-off-by: Gunnar Mills <213d3186dd7abf62ec3e856bb92d7b256149744c@us.ibm.com>

openbmc/phosphor-inventory-manager,openbmc/phosphor-inventory-manager