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

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https://hg.mozilla.org/integration/gaia-central/rev/596d2a4031c3
Author: Fernando Campo <fernando.campo@o2.com>
Desc: Merge pull request #16960 from fcampo/fix-jshint-fte

[FTE] Fixed some jshint errors (r=arcturus, f=julienw)

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https://hg.mozilla.org/integration/gaia-central/rev/d91a3f5b5bae
Author: Fernando Campo <fernando.campo@o2.com>
Desc: Bug 980344 - [FTE] Fixed some jshint errors
Bumping manifests a=b2g-bump