Do not set CONFIG_HEAT_AUTH_ENC_KEY
Do not set CONFIG_HEAT_AUTH_ENC_KEY

Use the default value (a random UUID) for CONFIG_HEAT_AUTH_ENC_KEY to
avoid https://bugs.launchpad.net/heat/+bug/1415887.

Change-Id: I89391fe7101125c6e0bb119567c3ac4bc169f3a4

sasukeh/packstack-vagrant,sasukeh/packstack-vagrant