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

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https://hg.mozilla.org/integration/gaia-central/rev/75d1bba9be13
Author: Dale Harvey <dale@arandomurl.com>
Desc: Bug 1040748 - Stop rocketbar title overlaying apps. r=kgrandon

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https://hg.mozilla.org/integration/gaia-central/rev/ca7e5db698ed
Author: Dale Harvey <dale@arandomurl.com>
Desc: Bug 1040753 - Remove unneeded task manager code in rocketbar. r=kgrandon

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https://hg.mozilla.org/integration/gaia-central/rev/2a229a8399b8
Author: Dale Harvey <dale@arandomurl.com>
Desc: Bug 1039995 - Hide HAIDA rocketbar on homescreen. r=kgrandon
Bumping manifests a=b2g-bump
Bug 1037128 - Regression: Contact API usage is being prompt on webpages r=fabrice
Bug 1037030 - Fix ContactManager.js permission prompting. r=gwagner