Set up cross-building for Scala 2.10 and 2.11

It would be great to have you library compiled for both 2.10 and 2.11.
I have set up cross-building by this guide: http://www.scala-sbt.org/0.13.5/docs/Detailed-Topics/Publishing.html
To activate a task for all the supported Scala version one need to prefix it with the plus sign "+":

\+ test
\+ publish
\+ makePom

I have checked out generated POM-files and they look valid. Tests also pass for all the versions.