XD-270 Adding spring-test testCompile dep
XD-270 Remove split read functionality for now
XD-270 Class renaming, Data to Entity

Renaming high level DataReader/DataWriter into
EntityReader/EntityWriter. Changes to other classes
to reflect this change.
XD-270 Class renaming, Storage to Data

Renaming high level StorageReader/StorageWriter into
DataReader/DataWriter. Changes to other classes
to reflect this change. Storage itself is not renamed,
just io classes in it.
XD-270 Refactoring writer model based on code review