Add support for i18n and l10n

The majority of the words on the site are user-generated, but I've tried
to surround everything else with localization calls. I don't know
another language so this will have to do until someone decides to
translate it lol

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

board/models.py

@@ -9,6 +9,7 @@ from django.core.files.base import ContentFile
 from django.dispatch import receiver
 from django.urls import reverse
 from django.utils import timezone
+from django.utils.translation import gettext as _
 from PIL import Image
 from io import BytesIO
 
@@ -152,11 +153,11 @@ class Post(models.Model):
         # Make sure there is at least some content
         self.text = self.text.strip()
         if not (self.text or self.image):
-            raise ValidationError("Please either write a message or upload an image")
+            raise ValidationError(_("Please either write a message or upload an image"))
         # Image upload size check
         if self.image and self.image.size > settings.MAX_UPLOAD_SIZE:
             raise ValidationError(
-                "Image supplied is too large. Maximum image size is %(max)s",
+                _("Image supplied is too large. Maximum image size is %(max)s"),
                 params={"max": settings.MAX_UPLOAD_SIZE},
             )
         # Rate limiting for posts
@@ -169,7 +170,8 @@ class Post(models.Model):
             if delta < self.board.post_cooldown:
                 cooldown = self.board.post_cooldown - delta
                 raise ValidationError(
-                    f"Please wait {int(cooldown.total_seconds())} seconds before posting again"
+                    _(f"Please wait %(cooldown)s seconds before posting again"),
+                    params={"cooldown": int(cooldown.total_seconds())},
                 )