Refactor backend names to pillow and wand

This uses absolute_import and refactors the backend names to pillow &
wand. It changes tests to use these names and also modified the test
runner to not pass any parameters concerning the image backends since the
defaults are enough for tests. It also fixes a minor bug that was occured
when the image file had already been read (multiple renditions in a single
page)

wagtail/wagtailimages/backends/__init__.py

@@ -38,7 +38,7 @@ def get_image_backend(backend='default', **kwargs):
     # Get configuration
     default_conf = {
         'default': {
-            'BACKEND': 'wagtail.wagtailimages.backends.pillow_backend.PillowBackend',
+            'BACKEND': 'wagtail.wagtailimages.backends.pillow.PillowBackend',
         },
     }
     WAGTAILIMAGES_BACKENDS = getattr(

wagtail/wagtailimages/backends/wand.py

@@ -1,6 +1,8 @@
+from __future__ import absolute_import
+
 from django.db import models
 from django.conf import settings
-from base import BaseImageBackend
+from .base import BaseImageBackend
 
 from wand.image import Image
 

wagtail/wagtailimages/models.py

@@ -190,8 +190,7 @@ class Filter(models.Model):
             self._parse_spec_string()
         
         # If file is closed, open it
-        if input_file.closed:
-            input_file.open()
+        input_file.open('rb')
         image = backend.open_image(input_file)
         file_format = image.format
 

wagtail/wagtailimages/tests.py

@@ -9,7 +9,7 @@ from wagtail.wagtailimages.models import get_image_model
 from wagtail.wagtailimages.templatetags import image_tags
 
 from wagtail.wagtailimages.backends import get_image_backend
-from wagtail.wagtailimages.backends.pillow_backend import PillowBackend
+from wagtail.wagtailimages.backends.pillow import PillowBackend
 
 def get_test_image_file():
     from StringIO import StringIO
@@ -123,7 +123,7 @@ class TestRenditionsWand(TestCase):
             title="Test image",
             file=get_test_image_file(),
         )
-        self.image.backend = 'wagtail.wagtailimages.backends.wand_backend.WandBackend'
+        self.image.backend = 'wagtail.wagtailimages.backends.wand.WandBackend'
 
     def test_minification(self):
         rendition = self.image.get_rendition('width-400')