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

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https://hg.mozilla.org/integration/gaia-central/rev/187de8e5a374
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #13765 from evhan55/920164

Bug 920164 - [MMS] Display the subject of an MMS, if present

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https://hg.mozilla.org/integration/gaia-central/rev/cdd160c80e97
Author: Evelyn Eastmond <evhan55@gmail.com>
Desc: Bug 920164 - [MMS] Display the subject of an MMS, if present

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https://hg.mozilla.org/integration/gaia-central/rev/f8e5c565b72d
Author: AndreiH <andrei.hutusoru@gmail.com>
Desc: Merge pull request #13907 from zacc/bug_941582

Bug 941582 - Python wait for save progress bar to clear when deleting/ed...

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https://hg.mozilla.org/integration/gaia-central/rev/6344bfe2c6d5
Author: Zac Campbell <zcampbell@mozilla.com>
Desc: Bug 941582 - Python wait for save progress bar to clear when deleting/editing photos