Bumping gaia.json for 2 gaia-1_2 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_2/rev/19a1c2650f1d
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 924454 - Lengthen the busy tone to 6 seconds r=etienne

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https://hg.mozilla.org/integration/gaia-1_2/rev/b11146297cec
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 924454 - Make the busy tone longer and clearer r=etienne