Don't automatically download sources (they don't exist for some of the deps)
bump scalastic to version 0.90.10.1, support for sbt 0.13.1 and scala 2.10.3

Dependencies were bumped for sbt 0.13.1 based on the supported versions here:
  https://groups.google.com/forum/#!topic/simple-build-tool/0AGST5qPbzw
Merge pull request #39 from martinb3/master

Source downloads fail for grizzled-slf4j, junit, scalatest, logback