Remove dict_sets.py to repalce with dict_set.py
Add dict_set.py for 'Dict/Set Lab'
Add safe_input.py
Add safe_input() to safe_input.py to handle EOFError and KeyboardInterrupt
Update safe_input.py/safe_input() to pass the input if exceptions are not raised
Add safe_input() to mailroom.py
Comment out all raw_input() and add safe_input()
Correct safe_input() to handle unicode.
Add safe_reprompt() to mailroom.py to handle the None returns from safe_input(). Remove all commented raw_input() calls