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

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https://hg.mozilla.org/integration/gaia-central/rev/5bfbed181778
Author: James Burke <jrburke@gmail.com>
Desc: Merge pull request #18773 from jrburke/bug1002932-email-stamp-cache-minify

Bug 1002932 - [email] cookie cache no longer working with GAIA_OPTIMIZE=1 r=asuth

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https://hg.mozilla.org/integration/gaia-central/rev/3a55d808c2e1
Author: jrburke <jrburke@gmail.com>
Desc: Bug 1002932 - [email] cookie cache no longer working with GAIA_OPTIMIZE=1
Bumping manifests a=b2g-bump