Fix so that scala-library with alternate naming can be found

Our team has bumped into a problem with Eclipse project generation on Play 2.2. I believe this is caused by http://www.scala-sbt.org/0.13.0/docs/Community/ChangeSummary_0.13.0.html#resolving-scala-dependencies in SBT 0.13. If we declare the scala version in sbt.boot.properties and play.boot.properties to be the same as what play is using the plugin works because scala-library.jar is used from .sbt/boot. But if we're using a different version of scala the scala-library.jar ends up in a different local repo (ivy) with a filename such as scala-library-2.10.3-RC3.jar.

This change makes the scala-library lookup more flexible so it can deal with files that include the version number in the filename.