[RFC] Add collection support/example

All done using annotations/expression, crazy right ? :)

Not using handlers (the resource one, that should be removed IMHO) feels way better. It's like there is only one way to do things with the library.

People should be able to subclass this classes to add properties/etc (though adding relations will break with json because #60). Or they could copy page and do their own stuff.

So, what do you think ? Flexible enough ?

Fixes #48