Making chart rerunnable with CM values defaults

[almahmoud]

Unless i'm misunderstanding how it works, I think rerunning the playbook doesn't work right now at least because all the passwords in CM values (https://github.com/CloudVE/cloudman-boot/blob/master/roles/cloudman-boot/templates/cm_chart_values.yml.j2#L20) are being auto-generated every run. This is bypassed in CloudLaunch model by overwriting these passwords in the injected values file, but perhaps we can think of a way to make it rerunnable in general, or at least better document the values that should be set and not auto-generated?
Not sure what the best solution is, but might make our dev easier