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

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https://hg.mozilla.org/integration/gaia-central/rev/40a905d4741f
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #18477 from KevinGrandon/bug_997751_homescreen_power_permission

Bug 997751 - [Homescreen] Remove 'power' permission from homescreen manifest

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https://hg.mozilla.org/integration/gaia-central/rev/b58494bba94b
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 997751 - [Homescreen] Remove 'power' permission from homescreen manifest r=GaryChen
Bumping manifests a=b2g-bump