* Use juju model as workspace and store in home
The current juju model will now be used as the tempest workspace name.
Additionally, all workspaces will be stored in ~/.tempest/<workspace>.
This patch also introduces a new option 'keep-workspace' that can be
specified along with other tempest options to keep the workspace after
tempest test execution. It defaults to False.
Also minor adjustment to smoke option to test boolean value.
