Integrate Scalariform

This pull request integrates Scalariform into the Play tasks.
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

This is the same formatting done by other Scala tools such as
the Scala IDE for Eclipse.
Merge pull request #34 from fernandoacorreia/code-style

Integrate Scalariform