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

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https://hg.mozilla.org/integration/gaia-central/rev/630e850efe1d
Author: Albert <acperez@tid.es>
Desc: Merge pull request #13515 from acperez/bug-936028

Bug 936028 - Remove appcache in hosted single variant apps to avoid wrong installation without internet connection. r=yurenju

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https://hg.mozilla.org/integration/gaia-central/rev/51d1d3f600ca
Author: Albert <acperez@tid.es>
Desc: Bug 936028 - Remove appcache in hosted single variant apps to avoid wrong installation without internet connection. r=yurenju