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

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https://hg.mozilla.org/integration/gaia-central/rev/8017299c3eb7
Author: Jim Porter <jporter@mozilla.com>
Desc: Merge pull request #24964 from jimporter/ringtone-now-playing

Bug 1029198 - [ringtones] Ringtone Manager should visually indicate whic...

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https://hg.mozilla.org/integration/gaia-central/rev/da637ea64860
Author: Jim <jporter@mozilla.com>
Desc: Bug 1029198 - [ringtones] Ringtone Manager should visually indicate which ringtone is being previewed; r=djf

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https://hg.mozilla.org/integration/gaia-central/rev/d3099e7bdad8
Author: Jim Porter <jporter@mozilla.com>
Desc: Merge pull request #11500 from jimporter/music-id3-improvements

Bug 841949 - Improve id3 parsing in the music app

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https://hg.mozilla.org/integration/gaia-central/rev/7dc0fe90905e
Author: Jim Porter <jporter@mozilla.com>
Desc: Bug 841949 - [music] Improve ID3 parsing
Bumping manifests a=b2g-bump