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

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https://hg.mozilla.org/integration/gaia-central/rev/57da16cd5729
Author: Jose Antonio Olivera Ortega <josea.olivera@gmail.com>
Desc: Merge pull request #14489 from jaoo/928297

Bug 928297 - [DSDS][Gaia] Settings app should support cellular & data settings of multiple sim cards. r=arthurcc

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https://hg.mozilla.org/integration/gaia-central/rev/8e4914b0263a
Author: Jose Antonio Olivera Ortega <josea.olivera@gmail.com>
Desc: Bug 928297 - [DSDS][Gaia] Settings app should support cellular & data settings of multiple sim cards

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https://hg.mozilla.org/integration/gaia-central/rev/ec760f98e960
Author: Greg Weng <snowmantw@gmail.com>
Desc: Merge pull request #14631 from snowmantw/issue949904

Bug 949904 - [LockScreen] When tap on the handle after dragged once, it sliding irregular toward the same side

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https://hg.mozilla.org/integration/gaia-central/rev/8a7e8953b4bc
Author: Greg Weng (snowmantw) <gweng@mozilla.com>
Desc: Bug 949904 - [LockScreen] When tap on the handle after dragged once, it sliding irregular toward the same side