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

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https://hg.mozilla.org/integration/gaia-central/rev/8c700813dda7
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #15324 from KevinGrandon/bug_959802_rocketbar_integration_tests

Bug 959802 - Rocketbar tests disabled

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https://hg.mozilla.org/integration/gaia-central/rev/1508fe8299ec
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 959802 - Rocketbar tests disabled