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

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https://hg.mozilla.org/integration/gaia-central/rev/5ba6f889689b
Author: Fernando Campo <fernando.campo@telefonica.com>
Desc: Bug 1016813 - [FTU] Update to use gaia-header (r=fcampo)
Bumping manifests a=b2g-bump