Remove cruft from solrmarc directory

Following from the last commit, this removes unnecessary properties
files from the solr/solrmarc project directory. It also updates the
remaining `config.properties` files to remove the illusion that the
`index.properties` file is still defined there. Now it is defined more
granularly in the haystack index class or the Solr backend.

Author: jthomale

solr/solrmarc/dev_config.properties

@@ -13,7 +13,8 @@
 
 # - solrmarc.indexing.properties -indicates how to populate Solr index fields from
 #   marc data.  This is the central configuration file for solrmarc.
-solrmarc.indexing.properties = dev_index.properties
+#   this is now controlled in Python via the haystack index object and custom Solr backend.
+# solrmarc.indexing.properties = dev_index.properties
 
 # - solrmarc.indexing.class - full name of java class with custom indexing functions. This
 #   class must extend SolrIndexer; Defaults to SolrIndexer.