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

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https://hg.mozilla.org/integration/gaia-central/rev/a17181ee689d
Author: Florin Strugariu <florin.strugariu@softvision.ro>
Desc: Merge pull request #26884 from bebef1987/marionette

Bug 1113133 - Update marionette version to 0.8.6

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https://hg.mozilla.org/integration/gaia-central/rev/95a48b183ea3
Author: bebef1987 <florin.strugariu@softvision.ro>
Desc: Bug 1113133 - Update marionette version to 0.8.6
Bumping manifests a=b2g-bump