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

========

https://hg.mozilla.org/integration/gaia-central/rev/4e3596b10de8
Author: James Burke <jrburke@gmail.com>
Desc: Merge pull request #21297 from jrburke/bug911412-email-view-icon

Bug 911412 - [Buri][fugu][Language][Email]The view the attachment Button is truncated r=jrburke

========

https://hg.mozilla.org/integration/gaia-central/rev/e4f160a2a0f1
Author: praveen.singapati <praveen.singapati@lge.com>
Desc: Bug 911412 - [Buri][fugu][Language][Email]The view the attachment Button is truncated

as per comments

small nit
Bumping manifests a=b2g-bump