Fix URITests to work under Windows
Merge pull request #1230 from dansanduleac/uri-tests

Fix URITests to work under Windows
Roll back sbt/sbt@482f99 (aggressive deletion of cache). Fixes #1091.

* sbt 0.12.3 introduced sbt/sbt@482f99 to fix #637 and #641.
* The underlying issue of #641 was an incorrect classifier, and it was
  fixed in sbt/sbt@718fa9 for #683 and shipped as sbt 0.13.0.