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

========

https://hg.mozilla.org/integration/gaia-central/rev/b38a312369ee
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #19240 from crdlc/bug-bug-1008586-v2

Bug 1008586 - [Homescreen] Missing collections icons

========

https://hg.mozilla.org/integration/gaia-central/rev/b15cb406636f
Author: crdlc <crdlc@tid.es>
Desc: Bug 1008586 - [Homescreen] Missing collections icons

========

https://hg.mozilla.org/integration/gaia-central/rev/ae5661566a90
Author: Wilson Page <wilsonpage@me.com>
Desc: Merge pull request #19197 from wilsonpage/1004524

Bug 1004524 - [Camera] Camera message about USB storage says 'Unplug...to view

========

https://hg.mozilla.org/integration/gaia-central/rev/99a38554dd2e
Author: Wilson Page <wilsonpage@me.com>
Desc: Bug 1004524 - [Camera] Update shared storage overlay text
Bumping manifests a=b2g-bump