Bumping gaia.json for 2 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/ddecb0524d95
Author: Julien Wajsberg <felash@gmail.com>
Desc: Merge pull request #11111 from TheoChevalier/Bug859035-unknown-size-author

Bug 859035 - [l10n] Do not use the same unknown entity for Size & Author...
r=julien

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https://hg.mozilla.org/integration/gaia-central/rev/e13a2b2fb4ae
Author: TheoChevalier <theo.chevalier11@gmail.com>
Desc: Bug 859035 - [l10n] Do not use the same unknown entity for Size & Author when installing a WebApp