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

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https://hg.mozilla.org/integration/gaia-2_1/rev/29bcdec54281
Author: Guillaume Marty <edo999@gmail.com>
Desc: Bug 1089451 - Swiping down from top edge when utility tray is already open and it closes; quite opposite from gesture's movement

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https://hg.mozilla.org/integration/gaia-2_1/rev/fa82b38c8dd4
Author: albertopq <apastor@mozilla.com>
Desc: Bug 1066847 - Adding tests to icons in the tray

Conflicts:
	apps/system/test/marionette/statusbar_icon_color_test.js

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https://hg.mozilla.org/integration/gaia-2_1/rev/50754d4ff527
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 1092161 - Properly handle MMI short-string codes r=drs

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https://hg.mozilla.org/integration/gaia-2_1/rev/d2f8bccc1736
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 1071542 - [Search] Blurry Settings Icon & incorrect alignment and sizing of string
Bumping manifests a=b2g-bump