Simplify the Serializer

This removes support for SimpleSerializer and JMSSerializer. This is in
order to centralize the format so we can specify a formal requirement.

To do this and share with others it uses bernard/normalt which makes
the delegation to other normalizers easier.

In the process DefaultMessage have gotten its internals refactored and
now uses __get/__set to support setting the variables instead of actual
properties (this is also a much better way of doing it).
Use normalt 0.2.0 pre-release
fix version constraints
use autoload-dev instead of bootstrap
use 1.0 of normalt