Added requirement on ext-xmlrpc

(ref #7)
Too many changes to list...

- Moved default XmlRpc Handler implementation to dedicated namespace
- Added XmlRpc Handlers implementation based on ext-xmlrpc
- Made loading of XmlRpc Handlers dependent on the ext being loaded or not
- Moved tests around
- Added phpunit.xml.dist + bootstraap
- Refactored Tests with Base class when applicable
Fixed namespaces import
Fixed tests