Make keystonerc and image file creation optional

In some cases keystone rc as well as image file
creation can be done manually before runtest execution,
also in Salt 2017.7 salt runner works unstable in case with
put local image file state. So this commit adds ability to disable
keystone rc and image file creation.

Change-Id: I86385ef7e3e1df069b108271b96fa86434e9074f
Related-Prod: https://mirantis.jira.com/browse/PROD-23915
3 files changed