Getting rid of confusing abstraction regarding formatter classes

Specifying the class directly is much less confusing and fragile.
Plus we have way too many things named 'type'.
Also changing MWEchoArticleLinkedFormatter to EchoArticleLinkedFormatter
to match the convention of the other formatter classes.
Also making EchoBasicFormatter the default, so that the Hello World
case is easier to implement.

Change-Id: Ibd9b15008d37ad815e466ab81ba9a5b668ee2791
Merge "Getting rid of confusing abstraction regarding formatter classes"