replaced 'csv_importer' with 'import_csv' in spec-file to reflect method name change in import_csv.rb
moar changes to import_csv.rb

* initialized @filenames so that an invalid filestring won't cause an undefined method error when Nilclass.include! is called
* cleaned up identify_and_unzip to handle different possible @file parameters
* removed parameter from move_to_import_directory method as @file is now ensured to be of type File if it is called