Simplify message/result serialization

[vxfield]

We could simplify the way our encoders work. For example:

1. Create a IResultEncoder and use some reflection for registering/invoking the encoders.
2. Create a generic encoder XsltResultEncoder<> : IResultEncoder, use a Xslt to transform the object to HTML or Text. The advantage for that is less code to maintain and make it more declarative using the templates. A factory could create generic sub-classes that take any parameters needed to customize the encoder and point to the Xslt files to encode Results to HTML and Text formats.