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

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https://hg.mozilla.org/integration/gaia-central/rev/a0bc29312d49
Author: Alive.Kuo <alegnadise@gmail.com>
Desc: Merge pull request #15346 from alivedise/bugzilla/959043/software-home-button-malfunction

Bug 959043 - Fix Software Home Button on Nexus4, r=timdream, r=gary

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https://hg.mozilla.org/integration/gaia-central/rev/277db93acbee
Author: Alive Kuo <alegnadise@gmail.com>
Desc: Bug 959043 - Fix Software Home Button on Nexus4