Implemented User access Key, and Account Creation

1.Implmented an access key system (like website cookies)
>Gives access key at login and can be verified against store hashed key.
 	This enables the system to quickly verify the user attempting
 	to view /  modify data was the last user to successfully log into
 	the account in question since the program started.

2.Implmented Logout function
>Destroys access key once its use has expired.
	A user must re-login to regenerate a valid access key.
 
3.Created User creation function
>Creates a new, valid user and adds it to the user list.
	The new user must have a unique and valid user name,
	and their password must at least 8 characters long.
	
4.Implemented a Salt generator.
>Generates a completely random alpha-numberical sequence of any length.

CHANGES

1. Removed Firstname/Lastname from user.  Specific data should be stored
   seperately and then linked to a user class (so access to data can be
   verified on the fly).