Stop QueryStringQuery from lowercasing search terms which have wildcards

When a search using kibana is being done, it ends up using the [query string query] (http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/query-dsl-query-string-query.html). Unless specified otherwise, queries that have wildcards in them are automatically lowercased (the search is case sensitive). This PR is supposed to avoid this kind of situations.