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

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https://hg.mozilla.org/integration/gaia-central/rev/c94fb9636998
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Merge pull request #15002 from dominickuo/bug-949016

Bug 949016 - [music] include the missing css file in open.html, r=jimporter

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https://hg.mozilla.org/integration/gaia-central/rev/928c52ba3121
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Bug 949016 - [music] include the missing css file in open.html
Bumping manifests a=b2g-bump