core: remove redundant image listing by pool

There is no need for a specific procedure (and specific DAO methods)
to get the list of ISO images for a Pool since it is possible to use
the regular getStorageDomainId method using the storage domain id
returned by getIsoStorageDomainIdForPool.

Change-Id: I6ed7de8141b73cec53899cf277a9fdfdc06f2fc1
Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>
core: unify GetImagesList using ImageFileType.All

It is possible to unify the two separate requests for Floppy and ISO
images using the enum ImageFileType.All. In order to do so the stored
procedures and the DAO methods have been updated to not filter by type
when ImageFileType.All is used.

Change-Id: I4e8fb85c3f0d58778b03fd0aa101d95bbeebf3f6
Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>