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

========

https://hg.mozilla.org/integration/gaia-central/rev/f8f59781300e
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #16661 from KevinGrandon/ZDroid-html5fact

Bug 965302 - [Feedback] clean up HTML r=kgrandon

========

https://hg.mozilla.org/integration/gaia-central/rev/a2f38862696f
Author: Zlatan Vasović <legospace9876@gmail.com>
Desc: Bug 965302 - [Feedback] clean up HTML r=kgrandon

========

https://hg.mozilla.org/integration/gaia-central/rev/eb397b8d2613
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Merge pull request #16184 from pivanov/bug-950147

Bug 950147 - Add new Illustrative Wallpapers for v.1.4

========

https://hg.mozilla.org/integration/gaia-central/rev/ab2de2191c8f
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 950147 - Add new Illustrative Wallpapers for v.1.4
Bumping manifests a=b2g-bump