MiqPassword is going away

[Fryguy]

@mshriver I am in the process of finalizing the removal of MiqPassword in favor of ManageIQ::Password (a separate gem). Technically the alias will stick around for some time so we don't break anything, but the goal is for it to go away. I see a lot of references in here, and I was going to make a PR, but I know that the code here deals with multiple versions simultaneously and I don't know how to deal with that. Just wanted to give you a heads up.