Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-1_4/rev/3897d2d4991e
Author: Michal Budzynski <michal@virtualdesign.pl>
Desc: Merge pull request #17390 from michalbe/polish-button-content

Bug 984315 - Fixing flexboxes in contact button
Conflicts:
	apps/communications/contacts/test/unit/views/details_test.js
Bumping manifests a=b2g-bump