fix 404 for adding

disattach ProposalEditMixin from AdditionalSpeaker's options.

Author: SivanYeh

src/proposals/views/speakers.py

@@ -71,7 +71,7 @@ class TutorialProposalManageSpeakersView(ProposalManageSpeakersView):
 
 class AdditionalSpeakerRemoveView(
         LoginRequiredMixin, UserProfileRequiredMixin,
-        ProposalEditMixin, FormValidMessageMixin, UpdateView):
+        FormValidMessageMixin, UpdateView):
 
     http_method_names = ['post', 'options']
     model = AdditionalSpeaker
@@ -89,7 +89,7 @@ def get_success_url(self):
 
 class AdditionalSpeakerSetStatusView(
         LoginRequiredMixin, UserProfileRequiredMixin,
-        ProposalEditMixin, FormValidMessageMixin, UpdateView):
+        FormValidMessageMixin, UpdateView):
 
     http_method_names = ['post', 'options']
     model = AdditionalSpeaker