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

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https://hg.mozilla.org/integration/gaia-central/rev/cd18c67ac910
Author: John Hu <johu@mozilla.com>
Desc: Merge pull request #11215 from huchengtw-moz/settings/Bug_897918_settings_app_should_use_hi-res_image

Bug 897918 - Settings app should use hi-res icons on hd phones, r=arthurcc

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https://hg.mozilla.org/integration/gaia-central/rev/8a92813acb82
Author: John Hu <johu@mozilla.com>
Desc: Bug 897918 - Settings app should use hi-res icons on hd phones