Update location of sbt in readme.
Add a new artifact in maven which is the precompiled incremental compiler interface
against the current version of scala.   While zinc doesn't actively use this, hte
IDE can directly use this when bundling an OSGi sbt artifact.
Merge pull request #1 from typesafehub/wip/republish-precompiled

Add additional precompiled artifact to the maven side of the fence