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

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https://hg.mozilla.org/integration/gaia-central/rev/461d907cc442
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #18349 from KevinGrandon/bug_995406_home2_install_uninstall_apps

Bug 995406 - [Home2] Support installing/uninstalling of applications

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https://hg.mozilla.org/integration/gaia-central/rev/6e87b9419f29
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 995406 - [Home2] Support installing/uninstalling of applications r=me a=gwagner
Bumping manifests a=b2g-bump