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

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https://hg.mozilla.org/integration/gaia-central/rev/9fecff8694dc
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Merge pull request #12573 from jmcanterafonseca/activity_error

Bug 918390 - [Contacts] No error when selecting a contact with no number...

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https://hg.mozilla.org/integration/gaia-central/rev/5afe33b330ca
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Bug 918390 - [Contacts] No error when selecting a contact with no number for Messages app contact requests

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https://hg.mozilla.org/integration/gaia-central/rev/42ef25aa33c1
Author: Amir Nissim <amirnissim@gmail.com>
Desc: Merge pull request #12581 from EverythingMe/921092-app-ordering

Bug 921092 - [e.me] Reverse order of newly added apps in Collections [r=...

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https://hg.mozilla.org/integration/gaia-central/rev/503d862696e6
Author: Amir Nissim <amirn@everything.me>
Desc: Bug 921092 - [e.me] Reverse order of newly added apps in Collections [r=ranbena]