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

========

https://hg.mozilla.org/integration/gaia-central/rev/aecb21f14843
Author: Jose Antonio Olivera Ortega <josea.olivera@gmail.com>
Desc: Merge pull request #21399 from jaoo/1016277

Bug 1016277 - If two different apps try to use the 'telephony' channel at the same time both apps can play audio. r=etienne_s

========

https://hg.mozilla.org/integration/gaia-central/rev/28bffa447724
Author: Jose Antonio Olivera Ortega <josea.olivera@gmail.com>
Desc: Bug 1016277 - Alternative to the second step: play silence during the call

========

https://hg.mozilla.org/integration/gaia-central/rev/56b53249c13e
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Merge pull request #21624 from Rik/find-contacts-when-removing-1029581

Bug 1029581 - Contact name is not shown in the call log after having two... r=drs

========

https://hg.mozilla.org/integration/gaia-central/rev/7a93c4d665ed
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Bug 1029581 - Contact name is not shown in the call log after having two contacts with same number and the first one is removed
Bumping manifests a=b2g-bump