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

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https://hg.mozilla.org/integration/gaia-1_4/rev/756387d4b6f3
Author: Florin Strugariu <bebef_1987@yahoo.com>
Desc: Merge pull request #20080 from AndreiH/bug_1020928

Bug 1020928 - [flame][v1.4] test_ftu_skip_tour.TestFtu is failing on v1.4

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https://hg.mozilla.org/integration/gaia-1_4/rev/ea4520c41085
Author: Andrei Hutusoru <andreihutusoru@P5069.(none)>
Desc: Bug 1020928 - [flame][v1.4] test_ftu_skip_tour.TestFtu is failing on v1.4
Bumping manifests a=b2g-bump