Added argument support to folder_size.py

I made it easier to tell which directory by the arguments supplied to calculate folder size. I am
trying to learn git and python so any comments is appreciated.

Author: Aaron

folder_size.py

@@ -8,8 +8,11 @@
 
 # Description   : This will scan the current directory and all subdirectories and display the size.
 
-import os       # Load the library module
-directory = '.' # Set the variable directory to be the current directory
+import os, sys       # Load the library module and the sys module for the argument vector
+try:
+    directory = sys.argv[1] # Set the variable directory to be the argument supplied by user.
+except IndexError:
+    sys.exit("Must provide an argument.")
 dir_size = 0    # Set the size to 0
 
 fsizedicr = {'Bytes': 1, 'Kilobytes': float(1)/1024, 'Megabytes': float(1)/(1024*1024), 'Gigabytes': float(1)/(1024*1024