Update NEWS for 1.15.4 release
Update NEWS for 1.15.4 release

xkahn/gvfs-cmis,xkahn/gvfs-cmis,halfline/gvfs,gicmo/gvfs,gicmo/gvfs,halfline/gvfs,gicmo/gvfs,halfline/gvfs,xkahn/gvfs-cmis,xkahn/gvfs-cmis,gicmo/gvfs