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

========

https://hg.mozilla.org/integration/gaia-central/rev/e355317309b0
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #12438 from bebef1987/bug-920449

Bug 920449 - Refactor test_cards_view_with_one_app.py

========

https://hg.mozilla.org/integration/gaia-central/rev/448bb2e702e7
Author: Bebe <bebe@mozilla.ro>
Desc: Bug 920449 - Refactor test_cards_view_with_one_app.py