Added a command-line tool to lists all user filestores and their corresponding users

Usage: list user filestores
-h,--help Prints a help text
--environment Show info about commandline environment
--nonl Remove all newlines (\n) from output
--responsetimeout <responsetimeout> response timeout in seconds for reading response from the backend (default 0s; infinite)
-A,--adminuser <adminuser> Admin username
-P,--adminpass <adminpass> Admin password
-c,--contextid <contextid> The id of the context
-m,--master_only Prints only the master user
-f,--filestore_id <id> The id of the filestore. Lists users for this filestore.