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

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https://hg.mozilla.org/integration/gaia-central/rev/e8c50e6a91ad
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #14307 from crdlc/bug-945668

Bug 945668 - [Download Manager] Adapt shared components to Download API

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https://hg.mozilla.org/integration/gaia-central/rev/0281c4ed71d6
Author: crdlc <crdlc@tid.es>
Desc: Bug 945668 - [Download Manager] Adapt shared components to Download API