Adapt admin configs to Django 1.8

from Django ChangeLog:

> Creating a ModelForm without either the 'fields' attribute or the 'exclude'
> attribute is prohibited

 ref #13

coin/isp_database/admin.py

@@ -12,6 +12,7 @@ class ISPAdminForm(ModelForm):
 
     class Meta:
         model = ISPInfo
+        exclude = []
 
     phone_number = FRPhoneNumberField(required=False,
                                       help_text='Main contact phone number')