Renamed drivef to driveLeft.  #5
Fixed #7
Renamed TestRepeatedly and fixed permissions on TestTee.
Renamed executeLeft to foldLeftM
Made Plan covariant in K again
Update build to allow for cross compile against scala 2.10.0.

This change includes:
 - Update sbt to 0.12.1
 - Update scalaz dependency to 7.0.0-M7 which is latest published stable
 - Update scalacheck to 1.10.0 which is only available against 2.9.2 and 2.10.0
 - Scalac option shenigans for 2.9.2 vs 2.10.0

Note: There are still a number of compiler warnings when building with 2.10.0,
      specifically non-exhaustive pattern matching on Process without handling
      return.