add dalvik low mem flag

http://review.cyanogenmod.org/#/c/47757/

Change-Id: Ib274cd26342caf04b60a7d9d66cf9e2ef3661790
rename max background apps property

http://review.cyanogenmod.org/#/c/47288/

Change-Id: Ia4b43988c4e6539cf257730d30ef3138119bc22d
update patches