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

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https://hg.mozilla.org/integration/gaia-1_4/rev/6acb6ab9a911
Author: Hubert Figuière <hub@figuiere.net>
Desc: Merge pull request #17624 from hfiguiere/bug988114

Bug 988114 - Hardcode the sha1 we want for the gaia-node-modules. r=yuren,kgrandon

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https://hg.mozilla.org/integration/gaia-1_4/rev/b029a2883648
Author: Arthur Chen <crh0716@gmail.com>
Desc: Merge pull request #17648 from Archaeopteryx/settings-bug988296-imsSettingsHeader

Bug 988296 - imsSettings-header points to messageSettings, should be imsSettings ('Message settings' vs. 'IMS settings'). r=arthurcc

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https://hg.mozilla.org/integration/gaia-1_4/rev/943eaa4e27b6
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #17320 from crdlc/bug-985132

Bug 985132 - [B2G][Homescreen]Input overlap with confirmation prompt whe...

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https://hg.mozilla.org/integration/gaia-1_4/rev/a72fc79794de
Author: Ben Kelly <bkelly@mozilla.com>
Desc: Merge pull request #17535 from wanderview/contacts-canvas-cleanup-2

Bug 983885: Aggressively cleanup img/canvas in contacts. r=jmcf
Bumping manifests a=b2g-bump