Bumping gaia.json for 4 gaia-central revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/2e80604eabd9
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #15049 from KevinGrandon/bug_956590_increase_email_test_timeout

Bug 956590 - Increase email test timeout r=me

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https://hg.mozilla.org/integration/gaia-central/rev/a1110d25ffc1
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 956590 - Increase email test timeout

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https://hg.mozilla.org/integration/gaia-central/rev/f44a91406f80
Author: George <georgeiscoming@gmail.com>
Desc: Merge pull request #15004 from cctuan/956004

Bug 956004 - define a marco for node.js command

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https://hg.mozilla.org/integration/gaia-central/rev/973f5cf6fae9
Author: cctuan <georgeiscoming@gmail.com>
Desc: Bug 956004 - define a marco for node.js command