Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/b3a73b86f977
Author: gasolin <gasolin@gmail.com>
Desc: Merge pull request #17496 from gasolin/sheriff981965

Bug 981965 - Remove browser menu top, r=timdream

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https://hg.mozilla.org/integration/gaia-central/rev/714378f10cf2
Author: Alive Kuo <alegnadise@gmail.com>
Desc: Bug 981965 - Remove browser menu top

Conflicts:
	apps/system/style/window.css

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https://hg.mozilla.org/integration/gaia-central/rev/5a1c3cae5ed3
Author: EragonJ <eragonj@eragonj.me>
Desc: Merge pull request #15550 from EragonJ/bug-960861

Bug 960861 - mozMobileConnections should not be requisites for airplane ...

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https://hg.mozilla.org/integration/gaia-central/rev/2d9d1677efc0
Author: EragonJ <eragonj@eragonj.me>
Desc: Bug 960861 - mozMobileConnections should not be requisites for airplane mode

- add Radio.js
- add Radio related tests
- use this radio service in ariplaneMode
Bumping manifests a=b2g-bump