webadmin: Remove Storage connection on import domain failure

Remove storage server connection if we failed to import an existing Storage Domain.

Change-Id: I553a311fe8856b9cd5825405fef39e91e4c6e771
Bug-Url: https://bugzilla.redhat.com/1136930
Signed-off-by: Maor Lipchuk <mlipchuk@redhat.com>
core: Add a warnning when OVF_STORE disks does not exists.

Add a warnning on attach operation to notify the user that there are no
backup componenets if the Storage Domain was handled before in a Data
Center version lower then 3.5

Change-Id: I79de5110898852a5bf3d46227aa7eef36a74a74a
Signed-off-by: Maor Lipchuk <mlipchuk@redhat.com>