Args can verify membership to a valid set of arguments
Added a TODO for Scalar
Added -,* to scalar ops
Added a unary negate in Scalar2
Added scalar division
Merge branch 'develop' of github.com:twitter/scalding into feature/optimizedmatrix
Args restrictTo method takes a Set[String] argument
Merge pull request #574 from tomtau/feature/optimizedmatrix

Feature/optimizedmatrix - added the missing Scalar operations
Bug Fix on scald.rb: Add User-Agent specification to prevent 403 Forbidden problems
Merge pull request #575 from IlldianX/develop

Bug fix on scald.rb: add User-Agent specification to prevent 403 Forbidden problems
Args restrictTo always allows scalding.*, tool.graph, and hdfs/local.
Merge pull request #573 from tresata/feat-restrict-args

Args can verify membership to a valid set of arguments