[FIX]Don't use password if not defined

[flotho]

proposal to fix #21

[ulvida]

Merci, @flotho !
Next wednesday we are moving ouyr office, but I'll see it after. Before testing, idea, for our DRY: maybe we could use module_defaults to factorize kvm common modules (almost all).

[ulvida]

Following up your MR (gitlab's PR) in the collection where this role has moved, I proposed you back a code improvement MR.

Let's continue there!

[flotho]

thanks