fix broken build for SBT 0.13 and support new sbt.testing test-interface

1) Change the Code to compile with SBT 0.13  ( it was unable to compile under SBT .13 due to the Test-Interface changes)
2) Replace the org.scalatools.testing  test-interface with new sbt.testing interface
3) changed the hard-coded "0.0" test time on "testcase" with newly added sbt.testing.Event.duration() method, now the testcase element is reporting run time in milliseconds
4) change the build.sbt version to 0.4.1-SNAPSHOT
5) add sbt-idea plugin in the project