I added an error check to 'Read Attribute' keyword in lib/rest_client.robot.
I added an error check to 'Read Attribute' keyword in lib/rest_client.robot.

Change-Id: Ibba76cef3b3795db4c2f6cebca661ad3bf3b512f
Signed-off-by: Michael Walsh <10404802c7de463f402c4a18638106ca1b12ef61@us.ibm.com>

openbmc/openbmc-test-automation,openbmc/openbmc-test-automation