clear Taxonomy table before to open proteins

ippisite/ippidb/management/commands/import_v1_data.py

 from django.core.management import BaseCommand
 import mysql.connector
-from ippidb.models import Bibliography, Protein
+
+from ippidb.models import Bibliography, Protein, Taxonomy
 
 class Command(BaseCommand):
 
@@ -48,6 +49,7 @@ class Command(BaseCommand):
             rows = cursor.fetchall()
             Protein.objects.all().delete()
             self.stdout.write(self.style.SUCCESS('Successfully flushed protein table'))
+            Taxonomy.objects.all().delete()
             for row in rows:
                 try:
                     p = Protein()