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
This is replacing the implementation I did for 'html-light'.
The reason html-light doesn't work is that we don't have any way
of reliably determining which parameter should be the one that is
linked to in the notification title (flyout notifications are only
supposed to have one link). With this system, the notification
definer can specify a separate message/params combination to use
specifically for the notification flyout. If they don't specify
these, it falls back to the normal title message/params.
Change-Id: I35394849cf99307eba4a76e079333d19514fdb5d
