re-add instance level config to indexer while keeping class level;  fixes missing whitelist and blacklist capabilities
collection_type field is now added in index_collection_druid method in indexer.rb and collection? method has been removed from solr_doc_builder
cosmetic refactor for specs
fix typo in spec
set up Nokogiri xml objects better in specs (fewer calls to Nokogiri)
change test config solr to be localhost just in case