Add image upload support

Images can be uploaded, thumbnails are created, they're displayed within
the threads themselves. Just like four chans!

There is not an upload size limit set yet. Gotta get on that next.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

board/urls.py

@@ -1,4 +1,6 @@
 from django.urls import path
+from django.conf import settings
+from django.conf.urls.static import static
 from board.views import *
 
 
@@ -8,3 +10,5 @@ urlpatterns = [
     path("<slug:url>/page/<int:page>/", BoardView.as_view(), name="board_detail"),
     path("<slug:url>/post/<int:id>/", PostView.as_view(), name="post_detail"),
 ]
+# TODO - make this conditional so we can serve images up with whatever server we want
+urlpatterns += static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)