defconfig: enable memory group

Required for optimal functionality of ZRAM

http://source.android.com/devices/low-ram.html

Signed-off-by: Dan Trifan <jimsth@gmail.com>
defconfig: set selinux to permissive for now

Signed-off-by: Dan Trifan <jimsth@gmail.com>
defconfig: updates from android recommended config

Signed-off-by: Dan Trifan <jimsth@gmail.com>