Remove length limit on token fields.

Their length is variable and depends on number of scopes.

Thanks @markus-lassfolk

esi/__init__.py

@@ -2,4 +2,4 @@
 
 default_app_config = 'esi.apps.EsiConfig'
 
-__version__ = '1.4.11'
+__version__ = '1.4.12'

esi/migrations/0005_remove_token_length_limit.py

@@ -0,0 +1,23 @@
+# Generated by Django 2.0.4 on 2018-04-30 00:06
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('esi', '0004_remove_unique_access_token'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='token',
+            name='access_token',
+            field=models.TextField(editable=False, help_text='The access token granted by SSO.'),
+        ),
+        migrations.AlterField(
+            model_name='token',
+            name='refresh_token',
+            field=models.TextField(blank=True, default='', editable=False, help_text='A re-usable token to generate new access tokens upon expiry.'),
+        ),
+    ]

esi/models.py

@@ -47,9 +47,9 @@ class Token(models.Model):
     """
 
     created = models.DateTimeField(auto_now_add=True)
-    access_token = models.CharField(max_length=254, help_text="The access token granted by SSO.",
+    access_token = models.TextField(help_text="The access token granted by SSO.",
                                     editable=False)
-    refresh_token = models.CharField(max_length=254, blank=True, null=True,
+    refresh_token = models.TextField(blank=True, default='',
                                      help_text="A re-usable token to generate new access tokens upon expiry.",
                                      editable=False)
     user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, blank=True, null=True,