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

========

https://hg.mozilla.org/integration/gaia-central/rev/4f9697599f1c
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #21826 from EverythingMe/1029977-b64toblob

Bug 1029977 - Do not use data-uris for collection backgrounds r=kgrandon

========

https://hg.mozilla.org/integration/gaia-central/rev/143199241b5a
Author: Amir Nissim <amirnissim@gmail.com>
Desc: Bug 1029977 - Do not use data-uris for collection backgrounds
Bumping manifests a=b2g-bump