Automated checkin: version bump for firefox 20.0 release. DONTBUILD CLOSED TREE a=release

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branch : GECKO200_2013032617_RELBRANCH
Added FIREFOX_20_0_RELEASE FIREFOX_20_0_BUILD1 tag(s) for changeset c90d44bfa96c. DONTBUILD CLOSED TREE a=release

--HG--
branch : GECKO200_2013032617_RELBRANCH