phosphor-ldap-conf: implement restore and add error handling

Upon startup, restore D-Bus properties from LDAP config file if
it exists.

Change-Id: I63b5a41eec8937ddbd5e8b4471936376602b6b0e
Signed-off-by: Nagaraju Goruganti <ngorugan@in.ibm.com>
2 files changed