task/ta-npi-017-01 -- extract item_nbr from job_item into exporter

nparcel/table/jobitem.py
* update collected_sql() method to extract job_item.item_nbr
task/ta-npi-017-01 -- extract item_nbr from job_item into exporter

nparcel/exporter.py
* updated the FIELDS global so caputre the new ITEM_NBR number
task/ta-npi-017-2 -- produce a list of column names within the current
cursor contex

nparcel/dbsession.py
* new method columns() which return a list of column names within the
  current cursor contex
task/ta-npi-017-03 -- provide exporter column support in config

nparcel/conf/nparceld.conf
* placeholder for the new exporter_fields config item which
  controls ordering via a comma separated list of indexes

nparcel/config.py
* support for new attribute exporter_fields
task/ta-npi-017-04 -- exporter report header generator

nparcel/exporter.py
* new attribute header which stores the collected_sql cursor context
  list of columns
* get_collected_items() method now sets the headers after the query
* new method get_header() to generate the exporter report header
task/ta-npi-017-05 -- integrate header generator into report()

nparcel/exporter.py
* deprecated the FIELDS global
* report() method signature now supports sequence tuple
* report() method output now generated by the new get_report_line()
  method
* refactor method get_report_line() so that it generates the exporter
  report line entry from any type of tuple-based input.  Signature
  feature new "line" argument

nparcel/exporterdaemon.py
* updated the _start() method so that config-based business unit
  sequence is fed into the report() method
task/ta-npi-017-06 -- job_item collected_sql() should be agent ID-aware

nparcel/table/jobitem.py
* updated the collected_sql() method so that it returns the Agent Id
task/ta-npi-017-07 -- prepare exporter for Ipec reporting

Makefile
nparcel/tests/__init__.py
* new test file class TestExporterIpec

nparcel/tests/test_exporter_ipec.py
* factor out Ipec specific test cases
task/ta-npi-017-08 -- signature file move for different file types

nparcel/exporter.py
* move_signature_file() method signature now includes "extension"
  attribute which represents the extension of the filename to move
* refactored the move_signature_file() method as existing layout was
  inefficient
task/ta-npi-017-09 -- config support for signature file transfer

nparcel/conf/nparceld.conf
* placeholders for the new "send_ps_file" and "send_png_file" flags

nparcel/config.py
* add support for the new "send_ps_file" and "send_png_file" flags