old_contents: 
  from django import forms
  from django.forms.models import ModelForm
  from djangocms_table.widgets import TableWidget
  from djangocms_table.models import Table
  from django.utils.translation import ugettext_lazy as _
  import csv
  from django.utils import simplejson
  
  
  class TableForm(ModelForm):
      table_data = forms.CharField(widget=TableWidget)
      csv_upload = forms.FileField(label=_("upload .csv file"), help_text=_("upload a .csv file to fill the table up."), required=False)
  
      def clean_csv_upload(self):
          if self.cleaned_data['csv_upload']:
              csv_reader = csv.reader(self.cleaned_data['csv_upload'], dialect='excel')
              data = []
              for row in csv_reader:
                  data.append(row)
              self.cleaned_data['table_data'] = simplejson.dumps(data)
              self.csv_uploaded = True
  
      class Meta:
          model = Table
          exclude = (
              'page',
              'position',
              'placeholder',
              'language',
              'plugin_type',
          )
  
new_contents: 
  from django import forms
  from django.forms.models import ModelForm
  from djangocms_table.widgets import TableWidget
  from djangocms_table.models import Table
  from django.utils.translation import ugettext_lazy as _
  import csv
  import json
  
  
  class TableForm(ModelForm):
      table_data = forms.CharField(widget=TableWidget)
      csv_upload = forms.FileField(label=_("upload .csv file"), help_text=_("upload a .csv file to fill the table up."), required=False)
  
      def clean_csv_upload(self):
          if self.cleaned_data['csv_upload']:
              csv_reader = csv.reader(self.cleaned_data['csv_upload'], dialect='excel')
              data = []
              for row in csv_reader:
                  data.append(row)
              self.cleaned_data['table_data'] = json.dumps(data)
              self.csv_uploaded = True
  
      class Meta:
          model = Table
          exclude = (
              'page',
              'position',
              'placeholder',
              'language',
              'plugin_type',
          )
  
subject: fix simplejson deprecation message