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

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https://hg.mozilla.org/integration/gaia-2_1/rev/2e2b6ccc0956
Author: Jim <jporter@mozilla.com>
Desc: Bug 1091137 - [ringtones] Fix clearing out the tonePlayer's state when hiding the app

Conflicts:
	apps/ringtones/js/tone_player.js

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https://hg.mozilla.org/integration/gaia-2_1/rev/37b2ce86fa76
Author: Paco Rampas <pacorampas@gmail.com>
Desc: Bug 1087026 - [2.1][l10n][cost control] Multiple locales: the line "use data alert" is overlapped by the toggle switch

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https://hg.mozilla.org/integration/gaia-2_1/rev/04d227f6d862
Author: Salvador de la Puente <salva@unoyunodiez.com>
Desc: Bug 1043762 - Volume buttons don't do anything in Settings and previewing new ringtones

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https://hg.mozilla.org/integration/gaia-2_1/rev/9743de7fdf0d
Author: Fernando Campo <fernando.campo@telefonica.com>
Desc: Bug 1077258 - Intermittent test failure - Fix FTU test
Bumping manifests a=b2g-bump