solr/conf/schema.xml: changed 'categories' to 'categories_id'
* updated 'indicator/templates/indicator/NewDeleteIndex.html':
  o page_condition: "all", "category", "search"
  o make use of django templates to generate contents
* updated 'indicator.views': GET, POST methods for NewDeleteIndex page
* indicator.search_indexes: changed 'categories' to 'categories_id'