SECRET_KEY is now generated by a script and stored as a local file

- key file ignored from git

Makefile

@@ -28,6 +28,9 @@ migrate:
 install:
 	# TODO: replace this with a proper setup.py
 	pip install -U -r requirements/base.txt
+	
+	# Generate a secret key
+	python InvenTree/key.py
 
 setup: install migrate