Suppress message; mkdir: path already exists

Running this:

$ ./calcyfy -g test_data_mrl/Glop_Pot/CATALOG.json 
Generating html from exsiting CATALOG.json file 
mkdir: path already exists: /home/mlake/git/CalcyteJS/test_data_mrl/Glop_Pot/metadata

To remove the message about an existing path use the -p option to mkdir like this:

shell.mkdir('-p', path.join(dir, 'metadata'))