Read CA cert from SVR DB for TLS

Read CA cert from SVR DB for TLS

Read and use CA cert from SVR DB for TLS
assuming that SVR DB has a Trust CA credential

Patch #1: Initial upload
Patch #2: API Renamed
Patch #3-4: Support for reading multiple cred & encoding types

Change-Id: Ibc930d6c8b0fa436077f1f71336489e0fb1e1ac6
Signed-off-by: Jongmin Choi <jminl.choi@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/10601
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Randeep Singh <randeep.s@samsung.com>