since qemu 1.7 xbzrle is AUTOMATICALLY enabled in the end of transfer - we need to explicit disable all feature we do not want

Signed-off-by: Stefan Priebe <s.priebe@profihost.ag>
remove unneeded parentheses
bump version to 3.1-15
QemuMigrate: print migration xbzrle if enabled (has xbzrlecachesize) for whatever reason (bug qemu, bug pve, ...)

Signed-off-by: Stefan Priebe <s.priebe@profihost.ag>
fix changelog