Fix some context values for can_modify in context

can_modify needs to be present in order to load the modify.js script.
This wasn't present on the PostView and was on a couple of unnecessary
views.

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

board/views.py

@@ -144,7 +144,6 @@ class PostCreateView(CreateView):
         context["capcodes"] = get_objects_for_user(
             get_user(self.request), "board.use_capcode"
         )
-        kwargs["can_modify"] = can_modify(self.request.user)
         return context
 
     def get_form_kwargs(self):
@@ -208,7 +207,6 @@ class ReplyCreateView(CreateView):
         context["capcodes"] = get_objects_for_user(
             get_user(self.request), "board.use_capcode"
         )
-        kwargs["can_modify"] = can_modify(self.request.user)
         return context
 
     def get_form_kwargs(self):
@@ -237,6 +235,7 @@ class PostView(TemplateView):
         post_id = self.kwargs["id"]
         kwargs["post"] = get_object_or_404(Post, id=post_id)
         kwargs["max_upload_size"] = settings.MAX_UPLOAD_SIZE
+        kwargs["can_modify"] = can_modify(self.request.user)
 
         return super(PostView, self).get_context_data(**kwargs)