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

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https://hg.mozilla.org/integration/gaia-central/rev/6486f2f21011
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #18807 from KevinGrandon/bug_1003409_home2_edit_mode_movement

Bug 1003409 - [Home2] Icon movement is too slow in edit mode

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https://hg.mozilla.org/integration/gaia-central/rev/b28e47214854
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1003409 - [Home2] Icon movement is too slow in edit mode r=me
Bumping manifests a=b2g-bump