Add admin capcodes

Sometimes, it is necessary for an admin or other moderator to reveal
themselves. Capcodes allow them to do so by appending a special colored
portion at the end of their name on a post.

This adds object-level permissions, so if you have a moderator who
shouldn't be able to use the "admin" capcode, you can give them
permission only to the "moderator" capcode.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

threadchat/settings.py

@@ -43,6 +43,7 @@ INSTALLED_APPS = [
     "django.contrib.messages",
     "django.contrib.staticfiles",
     "guardian",
+    "colorfield",
     "board",
 ]