Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/c541b74ca62d
Author: Carsten Book -Tomcat- <cbook@mozilla.com>
Desc: Revert "Bug 897352 - [gaia build system] Transition to a build_stage for assembling apps" build failure

This reverts commit c965501afb3849cb1b10b0738c86fe9e450e8b9a.
Bumping manifests a=b2g-bump