Impose a min and a max on time values in CONF.token
Impose a min and a max on time values in CONF.token

expiration is passed to datetime.timedelta which cannot handle Python
long values. Cap the integer at sys.maxsize. A negative time is also
invalid so set the minimum to 0.

Change-Id: Ie3ec0c490cac3b4c4cb87f246d6c8bc4e9b0d41a

ilay09/keystone,mahak/keystone,ilay09/keystone,rajalokan/keystone,openstack/keystone,mahak/keystone,rajalokan/keystone,openstack/keystone,openstack/keystone,mahak/keystone,rajalokan/keystone,ilay09/keystone