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

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https://hg.mozilla.org/integration/gaia-central/rev/8ad4396e8704
Author: Mitchell Van Der Hoeff <mitchell.vanderhoeff@gmail.com>
Desc: Bug 1069599 - Changed all gaia-subheaders in costcontrol to aria-level 2 with role="heading" r=salva

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https://hg.mozilla.org/integration/gaia-central/rev/53febc770e86
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Revert "Changed all gaia-subheaders in costcontrol to aria-level 2 with role="heading""

This reverts commit a32ad3e1cb738dbe4d4643cbbe5c9f3e5ee9d808.

Revert for not having the proper bug number in the commit message, bug 1069599.
Bumping manifests a=b2g-bump