removes from all search unused countNullValues param

data-discovery/src/main/java/vlkb/output/Dataset.java

...discovery/src/main/java/vlkb/output/SearchOutputData.java

data-discovery/src/main/java/vlkb/output/XmlSerializer.java

...overy/src/main/java/vlkb/webapi/FormatResponseFilter.java

data-discovery/src/main/java/vlkb/webapi/SearchServlet.java