Add option to change ivy2 location I think
Add sbt 0.12.1

And set that version.  Modify SBT_VERSION in bin/sbt
Make ant and sbt use the IVY2_REPO_DIR variable
Rework sbt stuff

Need to be able to run SBT packaged with other projects and use a
different ivy location, assuming those other projects use SBT_OPTS
Update packages