Skip purging REST/Redfish session post boot run

Changes:
      - Added flag for user to control the behaviour of default
        session delete to prevent function testing during BMC reset
        which relies on persistency of the session.

Change-Id: I0b6e8926af99a8a1ec8193c0afab823a2c606864
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/lib/resource.robot b/lib/resource.robot
index 91d81bb..4aa1a09 100755
--- a/lib/resource.robot
+++ b/lib/resource.robot
@@ -9,7 +9,10 @@
 
 # Transition REST vs Redfish ONLY temporary changes for stagging
 # automation infrastructure change and for continuity.
-${REDFISH_SUPPORT_TRANS_STATE}    0
+${REDFISH_SUPPORT_TRANS_STATE}    ${0}
+
+# By default Delete all Redfish session per boot run.
+${REDFISH_DELETE_SESSIONS}        ${1}
 
 ${OPENBMC_MODEL}  ${EMPTY}
 ${OPENBMC_HOST}   ${EMPTY}