bluez collection: add (moved from oe-core)

BlueZ 4.x Bluetooth stack has been removed from oe-core.
However, it is still supported, so add it to
recipes-connectivity in meta-oe.

meta-systemd layer bluez4 bbappend has been integrated
into bluez4 recipe.

In order to use it in oe-core/poky/YP, 'bluez5' backfill
distro feature needs to be disabled via:
DISTRO_FEATURES_BACKFILL_CONSIDERED = "bluez5" .
'bluetooth' distro feature needs to be present also.

Signed-off-by: Cristian Iorga <cristian.iorga@intel.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>