Adding generated factory package files to gitignore.

Change-Id: I3fac307fefacb83250f61cc85a84426632ef87c9

R=sosa@chromium.org,nsanders@chromium.org
BUG=None
TEST=Verified built factory packages stopped showing up in 'git status'.

Review URL: http://codereview.chromium.org/6759012
1 file changed