Bug 1101193 - Disable e10s on Nightly for several days before Aurora uplift. r=felipe, a=pref-only

Landing this directly on mozilla-central in order to ensure this gets into the
Nightly of November 24th, 2014. That's to ensure a solid week of non-e10s testing
on Nightly.

I felt this matched the 4th bullet for good reasons to land directly on mozilla-central
as listed here: https://wiki.mozilla.org/Tree_Rules#mozilla-central_.28Nightly_channel.29

--HG--
extra : rebase_source : 29e6342890785361517ad4ca22dc9dd44a436893
extra : amend_source : 5b1d730487f5b5e88a1850a95d59b9b50b8e3559