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

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https://hg.mozilla.org/integration/gaia-central/rev/fd17e1652112
Author: Yuren Ju <yurenju@gmail.com>
Desc: Merge pull request #12464 from yurenju/make-single-app

Bug 918295 - |APP=... make install-gaia| activate too many targets in th... r=@yurenju

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https://hg.mozilla.org/integration/gaia-central/rev/738318fffff4
Author: Vivien Nicolas <21@vingtetun.org>
Desc: Bug 918295 - |APP=... make install-gaia| activate too many targets in the build system