Fixes typo in scaladoc link in Readme
Tidied up ThermometerSpec ScaldingSupport and added some documentation.
Adds `withArgs` to ScaldingSupport.

Added a function to help create scalding job with the default and custom args.
Changes `withArgs` in ScaldingSupport to be type paramterised.
Fixes wrong test failure message for PathFacts.

Previously, most of the messages in PathFact would say the path exists
even though there were no files.
copy directory using FileUtils because FileSystem.copyFromLocal seems to sometimes prefix with source directory name