Added travis, coveralls and flake8

Author: yamijuan

manage.py

@@ -5,4 +5,5 @@
 if __name__ == "__main__":
     os.environ.setdefault("DJANGO_SETTINGS_MODULE", "preview_image_widget.tests.testsettings")
     from django.core.management import execute_from_command_line
-    execute_from_command_line(sys.argv)
+
+    execute_from_command_line(sys.argv)

preview_image_widget/tests/test_widget.py

@@ -1,11 +1,11 @@
-#coding: utf-8
+# coding: utf-8
 
 import django
 from django.conf import settings
 from django.test import TestCase
 
-from preview_image_widget.widgets import PreviewImageWidget
 from preview_image_widget.tests.utils import render_django110, render_django111
+from preview_image_widget.widgets import PreviewImageWidget
 
 
 class TestSimpleImageWidget(TestCase):

preview_image_widget/tests/utils.py

@@ -8,6 +8,7 @@
     def get_default_renderer():
         return None
 
+
 def render_django111(**kwargs):
     """
     Renders the widget using the django 1.11+ way
@@ -19,6 +20,7 @@ def render_django111(**kwargs):
     context = widget.get_context(kwargs['name'], kwargs['value'], kwargs['attrs'])
     return mark_safe(renderer.render('django/forms/widgets/input.html', context))
 
+
 def render_django110(**kwargs):
     """
     Renders the widget using the django 1.11+ way
@@ -28,4 +30,4 @@ def render_django110(**kwargs):
     final_attrs = {'type': 'file', 'name': kwargs['name']}
     final_attrs.update(kwargs['attrs'])
     html_expected = format_html('<input{} />', flatatt(final_attrs))
-    return html_expected
+    return html_expected

preview_image_widget/widgets.py

@@ -6,6 +6,7 @@ class PreviewImageWidget(FileInput):
     """
     Widget for displaying a image-preview in file fields.
     """
+
     def __init__(self, *args, **kwargs):
         """
         Adds a 'preview_image_widget' attr for the input