Better default Solr schema.xml

A client complained that he can't search for parts of a word in CKAN.
Compare [a search for tan](http://demo.ckan.org/dataset?q=tan) or [tan*](http://demo.ckan.org/dataset?q=tan*&sort=score+desc%2C+metadata_modified+desc&ext_bbox=&ext_prev_extent=-154.68749999999997%2C-80.17871349622823%2C154.68749999999997%2C80.17871349622823) to [a search for tanzania](http://demo.ckan.org/dataset?q=tanzania&sort=score+desc%2C+metadata_modified+desc&ext_bbox=&ext_prev_extent=-154.68749999999997%2C-80.17871349622823%2C154.68749999999997%2C80.17871349622823).

You can include the `EdgeNGramFilterFactory` into the schema.xml to make this possible.