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

========

https://hg.mozilla.org/integration/gaia-central/rev/c2ad1f367b62
Author: Gareth Aye <gaye@mozilla.com>
Desc: Merge pull request #16581 from gaye/kill-extra-copy-of-test-agent

Bug 976152 - Move test-agent off of npm r=lightsofapollo

========

https://hg.mozilla.org/integration/gaia-central/rev/3e6170bfc478
Author: Gareth Aye <gaye@mozilla.com>
Desc: Bug 976152 - Move test-agent off of npm r=lightsofapollo
Bumping manifests a=b2g-bump