merging trunk changes with IIS-CDH-5.3.0 branch
creating IIS-CDH-5.3.0 branch
#913 renaming DocumentContentUrl#contentSize to DocumentContentUrl#contentSizeKB changing field type from int to long, importing content size from ObjectStoreFile#fileSizeKB, updating dnet-objectstore-rmi dependency from 1.0.0 to 2.0.1-SNAPSHOT
#913 introducing DocumentContentUrl#contentSize field, handling it properly in all PIG transformers
introducing importer/plaintext/skip_extracted transformer required for plaintext import caching