Resolution to issue #469: Messages "Player has enter the game" and "Player has left the game" repeated twice.

I have removed three lines of code from the @OOC command in player.py that sends the message "Player has left the game", because this functionality is repeated in objects.py with the at_post_unpuppet function and results in the message "%s has left the game" to be repeated twice. 

I have also removed one line from the at_pre_puppet function in objects.py that sends the message "%s has entered the game", because it is repeated in the at_post_puppet function and results in the message "%s has entered the game" to be repeated twice.

Additionally, updated requirements.txt to correspond with the Getting Started page by changing the South version to >= 0.8.4 due to reported issues with version 0.8.2 and 0.8.3