added variable with path to server log file
added 'config' to .gitignore
fixed braces
Properly pass value of $SCREEN to as_user

Now passes the value of the variable rather than the literal '$SCREEN' to the as_user function when user requests the screen command.

(useful when this script is used to manage multiple instances for the same user in which case the screen attached would not necessarily be the one intended as the SCREEN variable was not used properly)