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

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https://hg.mozilla.org/integration/gaia-central/rev/513edc54944b
Author: Dave Hylands <dhylands@gmail.com>
Desc: Merge pull request #11136 from dhylands/dhylands-887751-Makefile-fix

Bug 887761 - Fix Makefile due to bustage. r=bustage

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https://hg.mozilla.org/integration/gaia-central/rev/d3ebb406d9e9
Author: Dave Hylands <dhylands@gmail.com>
Desc: Bug 887761 - Fix Makefile due to bustage. r=dhylands