Move attachment domains list to a separate module

boards/models/attachment/domains.py

@@ -0,0 +1,6 b''
+URL_DOMAINS = {
+    'meduza.io': 'meduza',
+    'youtube.com': 'youtube',
+    'youtu.be': 'youtube',
+    'wikipedia.org': 'wikipedia',
+}

boards/models/attachment/viewers.py

@@ -1,10 +1,11 b''
-import os
 import re
 
+from django.contrib.staticfiles import finders
+from django.contrib.staticfiles.templatetags.staticfiles import static
 from django.core.files.images import get_image_dimensions
 from django.template.defaultfilters import filesizeformat
-from django.contrib.staticfiles.templatetags.staticfiles import static
-from django.contrib.staticfiles import finders
+
+from boards.models.attachment.domains import URL_DOMAINS
 
 REGEX_DOMAIN = re.compile(r'(\w+\.)*(\w+\.\w+)')
 
@@ -46,13 +47,6 b' URL_PROTOCOLS = {'
     'magnet': 'magnet',
 }
 
-URL_DOMAINS = {
-    'meduza.io': 'meduza',
-    'youtube.com': 'youtube',
-    'youtu.be': 'youtube',
-    'wikipedia.org': 'wikipedia',
-}
-
 CSS_CLASS_IMAGE = 'image'
 CSS_CLASS_THUMB = 'thumb'