Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_4/rev/729757fa524c
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #20016 from AndreiH/bug_1020252

Bug 1020252 - [flame][v1.4] test_system_message.TestSystemMessages is failing on v1.4

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https://hg.mozilla.org/integration/gaia-1_4/rev/bd2ed7cc4907
Author: Andrei Hutusoru <andreihutusoru@P5069.(none)>
Desc: Bug 1020252 - [flame][v1.4] test_system_message.TestSystemMessages is failing on v1.4
Bumping manifests a=b2g-bump