Fix jar naming for cross-building

[pr1001]

Cross-builds seem to work but overwrite each previous language version built:

> +assembly
Setting version to 2.8.1
[info] Set current project to util (in build file:/Users/peter/Projects/Miogiro/Code/util/)
...
[info] Packaging /Users/peter/Projects/Miogiro/Code/util/target/util-assembly-0.1.jar ...
[info] Done packaging.
[success] Total time: 3 s, completed Nov 9, 2011 4:14:44 PM
Setting version to 2.9.1
[info] Set current project to util (in build file:/Users/peter/Projects/Miogiro/Code/util/)
... 
[info] Packaging /Users/peter/Projects/Miogiro/Code/util/target/util-assembly-0.1.jar ...
[info] Done packaging.
[success] Total time: 3 s, completed Nov 9, 2011 4:14:48 PM
Setting version to 2.9.1
[info] Set current project to util (in build file:/Users/peter/Projects/Miogiro/Code/util/)

The solution is to include the Scala version in the jar name. Basically, I would follow the sbt naming convention.

[eed3si9n]

The idea behind assembly is to be independent of the Scala version. If you want to include Scala version name, you can override jarName in assembly.

[pr1001]

Sorry, it wasn't clear to me that it was supposed to be independent of Scala versions.