Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/866d611e6368
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Revert "Bug 969472 - [B2G][Calendar] Events can still be tapped on and viewed when no calendar accounts are activated"

This reverts commit 0c9fe5806586fe46de83a787ada4fecc893081f0.
Bumping manifests a=b2g-bump