Fix readlink call on macOS, keep Linux compat (closes google#11)

enjarify.sh

@@ -36,7 +36,13 @@ else
 	echo "Using $PYTHON as Python interpreter"
 
 	# Find location of this bash script, and set its directory as the PYTHONPATH
-	export PYTHONPATH=$(dirname "$(readlink -f "${BASH_SOURCE[0]}")")
+	if [[ "$OSTYPE" == "darwin"* ]]; then
+		READLINK="readlink"
+	else
+		READLINK="readlink -f"
+	fi
+
+	export PYTHONPATH=$(dirname "$($READLINK "${BASH_SOURCE[0]}")")
 
 	# Now execute the actual program
 	exec $PYTHON -O -m enjarify.main "$@"