twitter: replace since_id with mentions_since_id

we'll want to treat the since_ids for mentions and (theoretical)
timelines differently, i think, so might as well just set up the split
out field now

dr_botzo/twitter/migrations/0005_replace_since_id_with_replies_specific_one.py

@@ -0,0 +1,23 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('twitter', '0004_add_mentions_output_channel_to_config'),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name='twitterclient',
+            name='since_id',
+        ),
+        migrations.AddField(
+            model_name='twitterclient',
+            name='mentions_since_id',
+            field=models.PositiveIntegerField(default=1, blank=True),
+        ),
+    ]

dr_botzo/twitter/models.py

@@ -14,12 +14,12 @@ class TwitterClient(models.Model):
 
     """Track twitter settings and similar."""
 
-    since_id = models.PositiveIntegerField()
     oauth_token = models.CharField(max_length=256, default='', blank=True)
     oauth_token_secret = models.CharField(max_length=256, default='', blank=True)
 
     mentions_output_channel = models.ForeignKey(IrcChannel, related_name='mentions_twitter_client', default=None,
                                                 null=True, blank=True)
+    mentions_since_id = models.PositiveIntegerField(default=1, blank=True)
 
     class Meta:
         permissions = (