Remove default query object.
Set default value of "changedFields" to false.
Check "fields" before use.
Use "_headers" and "_headerSent" to manage headers 
in Context instead of setting directly to response 
object. Make the Context more plugin friendly.
Rename "emitter" to "site".
Remove "emit" function.
The default option should not be modified.
Accepts options as View instance.
Separate the loading of "routes" and "apps".
Map apps and build routes at the time when we try 
to get listener.
Update tests.