For issue #17 process_components_cif script to read complete components.cif and produce PDBeChem ftp area

Currently fails test - because specifying output directory as None - currently not allowed:

        (new-rdkit-env3) [osmart@swannandrh6d pdbeccdutils]$ nosetests /ebi/msd/work2/osmart/ccd_utils/pdbeccdutils/tests/test_process_components_cif_cli.py
        usage: nosetests [-h] [--debug] COMPONENTS_CIF OUTPUT_DIR
        nosetests: error: the following arguments are required: COMPONENTS_CIF, OUTPUT_DIR
        .E...................................................................................................................
        ======================================================================
        ERROR: tests.test_process_components_cif_cli.test_input_file_that_cannot_exist_raises_system_exit
        ----------------------------------------------------------------------
        Traceback (most recent call last):
          File "/ebi/msd/work2/osmart/conda/envs/new-rdkit-env3/lib/python3.5/site-packages/nose/case.py", line 198, in runTest
            self.test(*self.arg)
          File "/ebi/msd/work2/osmart/ccd_utils/pdbeccdutils/tests/test_process_components_cif_cli.py", line 24, in test_input_file_that_cannot_exist_raises_system_exit
            output_dir=None, debug=False))
          File "/nfs/msd/work2/osmart/ccd_utils/pdbeccdutils/process_components_cif_cli.py", line 81, in process_components_cif
            create_directory_using_mkdir_unless_it_exists(output_dir)
          File "/nfs/msd/work2/osmart/ccd_utils/pdbeccdutils/utilities.py", line 27, in create_directory_using_mkdir_unless_it_exists
            os.mkdir(path)
        TypeError: mkdir: can't specify None for path argument
        -------------------- >> begin captured logging << --------------------
         : DEBUG: components_cif=/////impossible_to_open_file output_dir=None
        --------------------- >> end captured logging << ---------------------

        ----------------------------------------------------------------------
        Ran 117 tests in 2.090s

        FAILED (errors=1)