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

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https://hg.mozilla.org/integration/gaia-central/rev/c8d15d0a5f06
Author: Wilson Page <wilsonpage@me.com>
Desc: Merge pull request #22675 from wilsonpage/1050801

Bug 1050801 - Update shared/elements/gaia-header/ to ~v0.3.0

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https://hg.mozilla.org/integration/gaia-central/rev/9abed024881a
Author: Wilson Page <wilsonpage@me.com>
Desc: Bug 1050801 - Update shared/elements/gaia-header/ to ~v0.3.0
Bumping manifests a=b2g-bump