Finish redactions app

Signed-off-by: Roberto Rosario <roberto.rosario@mayan-edms.com>

mayan/apps/redactions/models.py

@@ -1,10 +1,5 @@
 from __future__ import unicode_literals
 
-import io
-
-from django.core.exceptions import ValidationError, NON_FIELD_ERRORS
-from django.db import models
-from django.utils.encoding import python_2_unicode_compatible
 from django.utils.translation import ugettext_lazy as _
 
 from mayan.apps.converter.models import Transformation