Integrate Scalariform

This pull request integrates Scalariform into the Play tasks, in preparation for resolving #29. 

The default configuration is used, which is the same configuration used by the Play Framework project and which follows the Scala Style Guide.

This pull request does **not** enforce following this style, will not fail commits or builds, and does **not** include 
reformatting of existing code.

It just makes available two reformatting commands:

`play scalariformFormat` to reformat main source code

`play test:scalariformFormat` to reformat test source code

That is the same formatting done by other Scala tools such as the Scala IDE for Eclipse.