Improve REST success rate by retry attempt

The changes involves:
    - Increase retry login session Authentication
    - Add delete sessions in utils

Resolves openbmc/openbmc-test-automation#94

Change-Id: Icad3044bbe0e9c345ed3633b5e72d6e170e3ed52
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
3 files changed