This makes all Bluetooth samples and tests being build with unified
kernel. main() is now executed from init thread and specifying task
for it in mdef file is no longer needed. By default main stack is
1024 bytes and this should be enough for BT samples.
Change-Id: I6674eea2c028b78ada5190acef72937186738af2
Signed-off-by: Szymon Janc <ext.szymon.janc@tieto.com>