shared/simplestreams: Add delta support
shared/simplestreams: Add delta support

Signed-off-by: Stéphane Graber <089afc6d81f66f1168a9849e15660feae286e024@ubuntu.com>

jsavikko/lxd,hallyn/lxd,erikmack/lxd,stgraber/lxd,hallyn/lxd,mjeanson/lxd,pcdummy/lxd,Skarlso/lxd,stgraber/lxd,lxc/lxd,mjeanson/lxd,hallyn/lxd,mjeanson/lxd,atxwebs/lxd,pcdummy/lxd,stgraber/lxd,stgraber/lxd,erikmack/lxd,erikmack/lxd,Skarlso/lxd,pcdummy/lxd,jsavikko/lxd,lxc/lxd,lxc/lxd,lxc/lxd,hallyn/lxd,hallyn/lxd,atxwebs/lxd,Skarlso/lxd,atxwebs/lxd,stgraber/lxd,lxc/lxd,jsavikko/lxd,stgraber/lxd,Skarlso/lxd,hallyn/lxd,lxc/lxd,stgraber/lxd,atxwebs/lxd,lxc/lxd