Update Translations (#2486)

Also included a Makefile recipe which makes use of the Crowdin CLI's `crowdin download` command. This requires whoever is using it to provide the project's API key in an environment variable, but we may automate this at some point.

Signed-off-by: Toby Harradine <tobyharradine@gmail.com>

Makefile

@@ -1,11 +1,19 @@
+# Python Code Style
 reformat:
 	black -l 99 -N `git ls-files "*.py"`
 stylecheck:
 	black --check -l 99 -N `git ls-files "*.py"`
+
+# Translations
 gettext:
 	redgettext --command-docstrings --verbose --recursive redbot --exclude-files "redbot/pytest/**/*"
-	crowdin upload
+upload_translations:
+	$(MAKE) gettext
+	crowdin upload sources
+download_translations:
+	crowdin download
 
+# Vendoring
 REF?=rewrite
 update_vendor:
 	pip install --upgrade --no-deps -t . https://github.com/Rapptz/discord.py/archive/$(REF).tar.gz#egg=discord.py