Automated checkin: version bump for fennec 21.0b2 release. DONTBUILD CLOSED TREE a=release

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branch : MOBILE210b2_2013041221_RELBRANCH
Added FENNEC_21_0b2_RELEASE FENNEC_21_0b2_BUILD2 tag(s) for changeset 4d506e99c792. DONTBUILD CLOSED TREE a=release

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branch : MOBILE210b2_2013041221_RELBRANCH