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

========

https://hg.mozilla.org/integration/gaia-central/rev/8f4eb4c0cc55
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #15222 from KevinGrandon/bug_934025_gallery_shared_padleft

Bug 934025 - [Media Apps] Use padLeft defined in format.js r=dmarcos

========

https://hg.mozilla.org/integration/gaia-central/rev/59b37bb4c6c3
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 934025 - [Media Apps] Use padLeft defined in format.js

========

https://hg.mozilla.org/integration/gaia-central/rev/bd835665d434
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #15221 from KevinGrandon/bug_934025_usage_shared_padleft

Bug 934025 - [Usage] Use padLeft defined in format.js r=salva

========

https://hg.mozilla.org/integration/gaia-central/rev/3051c5f0290c
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 934025 - [Usage] Use padLeft defined in format.js