Removed test classpath entry from ant project

As the ant project has no test dir this entry caused a clean
workspace to start with an error.
Added Eclipse .metadata to .gitignore
Open up support for arbitrary resource types

Introduced new extension interface ResourceRecognizer that delivers
the Resource implementation and/or set the appropriate mime-type.

Added defaults implementation, that provides identity and content
for any type of file, and a MetaType recognizer.