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

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https://hg.mozilla.org/integration/gaia-central/rev/4911c21ba545
Author: Jose Antonio Olivera Ortega <josea.olivera@gmail.com>
Desc: Merge pull request #15869 from jaoo/947855

Bug 947855 - Automatic selection of APN relying on the IMSI code in the ICC card. r=kaze

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https://hg.mozilla.org/integration/gaia-central/rev/17bc67b516e0
Author: Jose Antonio Olivera Ortega <josea.olivera@gmail.com>
Desc: Bug 947855 - Automatic selection of APN relying on the IMSI code in the ICC card
Bumping manifests a=b2g-bump