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

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https://hg.mozilla.org/integration/gaia-central/rev/b5c654a7a05f
Author: Arthur Chen <crh0716@gmail.com>
Desc: Merge pull request #13802 from EdgarChen/bug_939110

Bug 939110 - [system] Usage bar not showing in utility tray due to use w... r=salva

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https://hg.mozilla.org/integration/gaia-central/rev/c954463a496f
Author: Edgar Chen <echen@mozilla.com>
Desc: Bug 939110 - [system] Usage bar not showing in utility tray due to use wrong MobileConnection API