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

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https://hg.mozilla.org/integration/gaia-central/rev/17a5866a188b
Author: Miller Medeiros <miller@millermedeiros.com>
Desc: Merge pull request #19944 from millermedeiros/1019717-back-buttons

Bug 1019717 - [meta][Calendar] fix all cancel/back/X buttons r=gaye

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https://hg.mozilla.org/integration/gaia-central/rev/87d1abc2696c
Author: Miller Medeiros <miller@millermedeiros.com>
Desc: Bug 1019717 - [meta][Calendar] fix all cancel/back/X buttons
Bumping manifests a=b2g-bump