Bumping gaia.json for 3 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/a0fe2fdc571f
Author: Dale Harvey <dale@arandomurl.com>
Desc: Bug 1055593 - Migrate users history from old to new browser. r=qdot

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https://hg.mozilla.org/integration/gaia-central/rev/7b785e0794b5
Author: Sherman Chen <shamen.chens@gmail.com>
Desc: Bug 1059842 - Rocketbar app icon overflow r=kgrandon

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https://hg.mozilla.org/integration/gaia-central/rev/431d954f66ce
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Revert "Bug 1059482 - Rocketbar app icon overflow r=kgrandon"

This reverts commit 271c527d57c845e0c38b42deed91e8a89a137f1a.

Reverting for incorrect bug listed in commit message. Proper bug is: bug 1059842
Bumping manifests a=b2g-bump