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

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https://hg.mozilla.org/integration/gaia-central/rev/da4701c2fd9a
Author: Yura Zenevich <yura.zenevich@gmail.com>
Desc: Merge pull request #20402 from yzen/bug-1024131

Bug 1024131 - updated homescreen app icons' role to link for consistency...

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https://hg.mozilla.org/integration/gaia-central/rev/86a78a62d31d
Author: Yura Zenevich <yzenevich@mozilla.com>
Desc: Bug 1024131 - updated homescreen app icons' role to link for consistency with other apps. r=crdlc
Bumping manifests a=b2g-bump