Switch to linaro-4.8-14.04 toolchain

Change-Id: I41b45d1213882313e81de71230f92d4839322f9e
fstab: Run fsck on /persist too.

This partition gets no activity, but it can still get corrupted by
unclean shutdowns; fsck all the things

Change-Id: I60c08b5d3157e582c96f5131fd0195dd591f6fc1