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

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https://hg.mozilla.org/integration/gaia-central/rev/78a18bc9c0e6
Author: Carmen Jiménez <cjc@tid.es>
Desc: Merge pull request #16048 from mcjimenez/bug923449

Bug 923449 - SV: Network Display Indicator customization by SIM

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https://hg.mozilla.org/integration/gaia-central/rev/ae4547ab7b6b
Author: Carmen Jimenez Cabezas <cjc@tid.es>
Desc: Bug 923449 - SV: Network Display Indicator customization by SIM
Bumping manifests a=b2g-bump