build nickname can be specified with the
  -Dbuild.nickname=somename
and the build version can be specified with
  -Dbuild.version=someversionstring
These will default to development and head-rXXXX where XXXX is the revision
number of the svn checkout or Unknown if the revision number cannot be determined.
Note: This will be extended later.

The buid nickname and build version are placed in the MANIFEST.MF of the dacapo.jar
as Specification-Version and Implementation-Version respectively---this needs to be
checked for sanity.