DDF-894 Added propertyIsNull support to the SolrFilterDelegate

-kind of odd to get this to work.  First you come in without a field type so we have to do so using the getAnonymousField() method.  Than we have to use the negative queries to actually get the results we need. (*:* -fieldName:[* TO *]) is the magic sause to get this to work.  For details on how this works, visit the url below.
-http://stackoverflow.com/questions/17044661/how-to-filter-search-by-values-that-are-not-available/17045097#17045097
I might be missing something, but he's just using the diamond operator that is valid for java 7 and above (https://docs.oracle.com/javase/jp/8/technotes/guides/language/type-inference-generic-instance-creation.html).