task/ta-npi-017-15 -- sort report items based on JOB_KEY

nparcel/exporter.py
* new method get_header_column() which returns the index position of a
  given header token
* updated the report() method so that it sorts line items on JOB_KEY
task/ta-npi-017-13 -- ftp to pick up *.png files

nparcel/ftp.py
* updated the process() method to source *.png files in addition to
  *.ps files
task/ta-npi-017-14 -- report filename needs to be based on BU

nparcel/exporter.py
* update the report() and outfile() method signature to include the
  "identifier" argument for BU-specific filename creation
* outfile() method now support an BU identifier in the filename creation

nparcel/exporterdaemon.py
* patched a bug in the sequence generator in the _start() method
task/ta-npi-017-14 -- report filename needs to be based on BU (cont)

nparcel/tests/test_exporter.py
* patch bug in the test_output_file_creation test