Fix duplicate <dataDir> in 'solrconfig.xml' for Solr 4.5.0.

Solr 4.5.0 is stricter when parsing 'solrconfig.xml' and will fail to start due to duplicate <dataDir> nodes in the file: fix that.

Also explicitly declare the template files as package data, since when installing directly from a tarball with 'pip', the template files weren't being installed.