Another major Pinry model rewrite

Generate thumbnail and standard image on request, and use
http://github.com/mirumee/django-images for generating them. Also,
remove the CreatePin page as pin creation is going to be done
in JavaScript. Create UploadImage view for uploading images from
computer.

pinry/pins/forms.py

@@ -1,44 +1,9 @@
 from django import forms
 
-from .models import Pin
+from django_images.models import Image
 
 
-class PinForm(forms.ModelForm):
-    url = forms.CharField(required=False)
-    image = forms.ImageField(label='or Upload', required=False)
-
-    _errors = {
-        'not_image': 'Requested URL is not an image file. Only images are currently supported.',
-        'pinned': 'URL has already been pinned!',
-        'protocol': 'Currently only support HTTP and HTTPS protocols, please be sure you include this in the URL.',
-        'nothing': 'Need either a URL or Upload',
-    }
-
+class ImageForm(forms.ModelForm):
     class Meta:
-        model = Pin
-        fields = ['url', 'image', 'description', 'tags']
-
-    def clean(self):
-        cleaned_data = super(PinForm, self).clean()
-
-        url = cleaned_data.get('url')
-        image = cleaned_data.get('image')
-
-        if url:
-            image_file_types = ['png', 'gif', 'jpeg', 'jpg']
-            if not url.split('.')[-1].lower() in image_file_types:
-                raise forms.ValidationError(self._errors['not_image'])
-            protocol = url.split(':')[0]
-            if protocol not in ['http', 'https']:
-                raise forms.ValidationError(self._errors['protocol'])
-            try:
-                Pin.objects.get(url=url)
-                raise forms.ValidationError(self._errors['pinned'])
-            except Pin.DoesNotExist:
-                pass
-        elif image:
-            pass
-        else:
-            raise forms.ValidationError(self._errors['nothing'])
-
-        return cleaned_data
+        model = Image
+        fields = ('image',)