core: Reordered members in LUNs class

Moved all the LUNs class members to the head of the file.

Change-Id: Ifeeafc1482c98cdf5e991caff67e952c0db0820d
Signed-off-by: Idan Shaby <ishaby@redhat.com>
core: Added toString() to LUNs class

Change-Id: I12a1807283e00b0419a3b7ca6e719c9ca747cde6
Bug-Url: https://bugzilla.redhat.com/1101737
Signed-off-by: Idan Shaby <ishaby@redhat.com>