new Update Processor's to automatically add fields with new UUIDs and Timestamps to SolrInputDocuments leveraging SOLR-2802. Both processors should default to selecting the uniqueKey field if it is the appropriate type.
This is necessary for 4.0 because of SOLR-2796
AddUpdateCommand.getIndexedId doesn't work with schema configured defaults/copyField - UUIDField/copyField can not be used as uniqueKey field
update javadocs for DateField, TrieDateField, and UUIDField to warn about using NEW/NOW default in SolrCloud