Add support for optional debug parameters
Update debug documentation for clarity and accuracy
Add printFields and printTuple interval support
sumByLocalKeys, Counters and Task Numbers
Fixed bug in package.scala.
Bumped version to 0.9.0rc4 in package.scala.
Throw a more informative error when failing to validate sources.
Merge pull request #683 from azymnis/validation_error

Throw a more informative error when failing to validate sources.
Merge pull request #682 from stephanh/bug_fix

Fixed bug introduced in #676
Added failing test for matrix2 serialization.
Changed chill version to 0.3.5.
Fixed serialisation issues in Matrix2 Product.
Changed Matrix2 tests to use runHadoop instead of run.
Merge pull request #684 from stephanh/matrix2_serialization

Matrix2 serialisation has issues
Added debug method to ValuePipe.
Clean up Args+Mode coupling
use better constructor in test to see exceptions
Put in the mode on clone
Fix + on ArgsMode
Add IRC notification support to .travis.yml