Fixed the request workflow when a pre-provisioning dialog is used

Several adjustments in the code were done to accommodate the
pre-provisioning dialog prior to the main provisioning dialog in the
request workflow.

https://bugzilla.redhat.com/show_bug.cgi?id=1108918
Merge pull request #113 from AparnaKarve/vm_preprovisioning_dlg_bz1108918

Fixed the request workflow when a pre-provisioning dialog is used