Changes in document-classification

* old Chrum's Java and Bash files removal
* new UDF EXTRACT_DOCUMENT_METADATA to extract DocumentMetadata field from DocumentWrapper bytearray
* amended UDF EXTRACT_MAP_WHEN_CATEG_LIM for purposes of extracting either metadata in given language or in all languages
* new, simplified workflow dc-train-model-short with implicit (%DEFAULT) parameters of lower impact on a workflow
* new macro for reading data from HDFS in a specified way
* new way of reading documents into model creation Pig script in document-classification