engine_page: ovirt.node.config.defaults SSH

Use SSH class from ovirt.node.config.defaults to enable SSH password
authentication, persist the files and update the node config file.
Thanks to Fabian Deutsch

Change-Id: I03dda8474aac4c37859a50dd9c1a2a68dc046f6d
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=901497
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>