Bumping gaia.json for 3 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/324804537eae
Author: crdlc <crdlc@tid.es>
Desc: Bug 1021518 - [Vertical Homescreen] Hitting home button on lockscreen make the homescreen goes up after unlock r=kgrandon

========

https://hg.mozilla.org/integration/gaia-central/rev/9e0f1747ae93
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #20043 from khuey/createListItemLeak

Bug 1020685: Close only over the URL string that we need. r=bfrancis

========

https://hg.mozilla.org/integration/gaia-central/rev/c18ea8366d17
Author: Kyle Huey <khuey@kylehuey.com>
Desc: Bug 1020685: Close only over the URL string that we need. r=bfrancis
Bumping manifests a=b2g-bump