inital commit for signup

added a basic app using the UserCreationForm to create new user at /accounts/signup/
change outside of the app are:
-added signup to INSTALLED_APPS in /photo21/settings.py
-added accounts/signup/ to path in /photo21/urls.py

should extend UserCreationForm to have field for email and maybe first/last names, except if we want the user to add that themselves later

signup/apps.py

@@ -0,0 +1,4 @@
+from django.apps import AppConfig
+
+class Signup(AppConfig):
+    name = 'signup'