webadmin: Enabled WAD for File Domains in the UI

This patch enables the "Wipe After Delete" check box for file domains in
the windows "Add Virtual Disk" and "Edit Virtual Disk".

Change-Id: Ib8b9f2860fd186651311814d0087c47f4083c863
Bug-Url: https://bugzilla.redhat.com/1122510
Signed-off-by: Idan Shaby <ishaby@redhat.com>