Make sure addSbtModule will work in sbt 1
Make sure addSbtModule will work in sbt 1

For some reason using ClasspathDependency doesn't work in sbt 1, while
ClasspathDep[ProjectReference] does. The latter is less specific and
works just as well.

xuwei-k/xsbt,xuwei-k/xsbt,xuwei-k/xsbt,mdedetrich/sbt,sbt/sbt,sbt/sbt,mdedetrich/sbt,sbt/sbt,mdedetrich/sbt,mdedetrich/sbt,xuwei-k/xsbt,sbt/sbt,Duhemm/sbt,Duhemm/sbt,mdedetrich/sbt,sbt/sbt,sbt/sbt,sbt/sbt,mdedetrich/sbt,mdedetrich/sbt,xuwei-k/xsbt