Move to using postgresql

- Need to write a shell script to automate db install
- For now:
   - https://gist.github.com/sirodoht/f598d14e9644e2d3909629a41e3522ad
   - https://www.digitalocean.com/community/tutorials/how-to-use-postgresql-with-your-django-application-on-ubuntu-14-04

InvenTree/InvenTree/settings.py

@@ -106,8 +106,13 @@ WSGI_APPLICATION = 'InvenTree.wsgi.application'
 
 DATABASES = {
     'default': {
-        'ENGINE': 'django.db.backends.sqlite3',
+        'ENGINE': 'django.db.backends.postgresql',
-        'NAME': os.path.join(BASE_DIR, 'inventree_db.sqlite3'),
+        'NAME': 'inventree',
+        'USER': 'inventreeuser',
+        'PASSWORD': 'inventree',
+        'HOST': 'localhost',
+        'PORT': '',
+        #'NAME': os.path.join(BASE_DIR, 'inventree_db.sqlite3'),
     }
 }