Add configer module
Update configer.py: add 'read_config' function
Update configer.py: add argument setting
Update configer.py: change 'config_file_loc' default
Update configer.py: add 'configer' object
Update configer.py: add 'self.'
Fix configer.py: configuration file location
Update configer.py: change configuration file name to 'gcli.ini'
Update configer.py: finish 'set_arguments' function
Update configer.py: add default value
Update create_command.py: implement configer class
Update delete_command.py: implement configer class
Update tool.py: make '<user_name>' optional
Update list_command.py: implement configer class
Merge branch 'feature-config_file' into dev