webadmin: disks tab - add listeners on presenter

Adding disk type (All/Image/LUN) change event lister
on 'MainTabDiskPresenter -> onReveal' in order
to ensure listener subscription (currently, since the
listeners are added in the view, it might get
cleared upon staling the list model).

Change-Id: I0a0e76d5c21c1420232b12a6cbf2d65ff2851c09
Bug-Url: https://bugzilla.redhat.com/1019659
Signed-off-by: Daniel Erez <derez@redhat.com>