Add line-break after exported fields

Match the Golang std library style of adding line-breaks after exported
fields.

http://golang.org/src/pkg/sync/cond.go?s=609:772#L12
Add StringToString transformer

In some cases we'll want to save the data from the stream directly with
no transformation needed. This will allow us to return the raw data
string from the stream

* Add new StringToStringTransformer
* Use interface instead of Record