Partially revert "Checks whether to add Atmos shim or not based on Atmos supported versions of Akka and Play."

This reverts commit cd9eddb7f288dbbc4c21f95aff3d3ccd8ed00f2a.

Reverting the probe changes but keeping the version info in the build.
Create atmos plugin .sbt files or not depending on akka/play version

We already never created these files for sbt 0.12 projects so we
continue that.

Build info added to integration tests so they automatically stay
in sync with the latest version we claim to support.
Merge pull request #62 from sbt/wip/havocp-conditional-atmos-add

Only add atmos .sbt files if akka/play version is correct