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

========

https://hg.mozilla.org/integration/gaia-central/rev/4896fa8ee0e8
Author: gasolin <gasolin@gmail.com>
Desc: Merge pull request #18724 from gasolin/issue-997595

Bug 997595 - [NFC] Long press home button still can work while NFC is pa..., r=alive

========

https://hg.mozilla.org/integration/gaia-central/rev/e222857b8523
Author: gasolin <gasolin@gmail.com>
Desc: Bug 997595 - [NFC] Long press home button still can work while NFC is pairing
Bumping manifests a=b2g-bump