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

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https://hg.mozilla.org/integration/gaia-central/rev/e6a1b900f2f7
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #13673 from KevinGrandon/revert_bug_935307

Revert "Bug 935307 - [B2G][Contacts] A user is able to retrieve a contact information from Settings screen"

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https://hg.mozilla.org/integration/gaia-central/rev/b2a735ae7abd
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Revert "Bug 935307 - [B2G][Contacts] A user is able to retrieve a contact information from Settings screen"

This reverts commit 256dcfe2cbe03640888fb0ca8fd09d3deece4863.