title: Django import-export display manytomany as a name instead of ids when exporting to csv
body: <p>How do I display a manytomany column as a list of names instead of ids using <code>Django import-export</code>?</p>
  
  <p>Currently my models and resources.py looks like this and returns a csv with a list of ids for the <code>country</code> column:</p>
  
  <p><strong>models.py</strong></p>
  
  <pre><code>class Country(models.Model):
      name = models.CharField(max_length=50, null=False,
                              blank=False, unique=True)
  
      def __str__(self):
          return self.name
  
  
  class Species(models.Model):
      name = models.CharField(max_length=50, null=False, blank=False)
      country = models.ManyToManyField(Country)
  
      def __str__(self):
          return self.name
  </code></pre>
  
  <p><strong>resources.py</strong></p>
  
  <pre><code>from import_export import resources,fields
  from import_export.widgets import ManyToManyWidget
  from .models import Species, Country
  
  class SpeciesResource(resources.ModelResource):
      country=fields.Field(attribute='country', widget=ManyToManyWidget(Country), column_name='Country')
      name = fields.Field(attribute='name', column_name='Name')
      class Meta:
          model = Species
          fields =('name','country')
          export_order = fields
  </code></pre>