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

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https://hg.mozilla.org/integration/gaia-central/rev/2d259d659aa7
Author: Florin Strugariu <bebef_1987@yahoo.com>
Desc: Merge pull request #13510 from zacc/bug_936364

bug 936364 Address test_settings_wallpaper.py intermittent

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https://hg.mozilla.org/integration/gaia-central/rev/5e2ee581ce47
Author: Zac Campbell <zcampbell@mozilla.com>
Desc: bug 936364 Address test_settings_wallpaper.py intermittent

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https://hg.mozilla.org/integration/gaia-central/rev/4de9ba817034
Author: Ben Kelly <bkelly@mozilla.com>
Desc: Merge pull request #13487 from wanderview/contacts-avoid-imgloader-reload

Bug 936202: Defer imgLoader.reload() when inserting contacts.  r=jmcf

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https://hg.mozilla.org/integration/gaia-central/rev/1345191d46a2
Author: Ben Kelly <ben@wanderview.com>
Desc: Bug 936202: Defer imgLoader.reload() when inserting contacts.