packaging: suggest path for local storage during AIO setup

When running AIO setup, the installer suggest a default location
(/var/lib/images) for the Local storage domain path the same way
we suggest for the local ISO domain.

Renamed generateIsoDomainName in generateIsoDomainPath in
engine-setup to be more accurate.

Bug-Url: https://bugzilla.redhat.com/896465
Change-Id: I9ddc2810ab3a6c2c20ce8b7663a813e89312f4d1
Signed-off-by: Sandro Bonazzola <sbonazzo@redhat.com>
(cherry picked from commit b1e0cf6614cc67d4832cf41e90e3f7898b78fd06)