Workaround Heat not handling token expiry

Heat cannot handle a token expiring mid-deploy. Until the heat bug is
fixed we can workaround it by upping the token expiry time. The value
of 4 hours is higher than the time we need to deploy a 30 node cloud
of real hardware, and less than the 5 hour upper maximum suggested by
Morgan Fainberg, Keystone core.

Change-Id: Ib079f8880b3672ac442804557baca954e8af87ff
Partial-Bug: #1306294
Merge "Workaround Heat not handling token expiry"