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

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https://hg.mozilla.org/integration/gaia-central/rev/70b0efc9b76e
Author: James Lal <james@lightsofapollo.com>
Desc: Merge pull request #13217 from lissyx/bug931718-v2-gaia

Bug 931718 - Introduce a 'print-xulrunner-sdk' make target

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https://hg.mozilla.org/integration/gaia-central/rev/f471b0e591ed
Author: Alexandre Lissy <lissyx+github@lissyx.dyndns.org>
Desc: Bug 931718 - Introduce a 'print-xulrunner-sdk' make target

In order to be able to run mochitest-remote, for example on emulator, we
need to have a way to get the correct path of the XULRunner SDK.