fix: Fix 502 error on editing course metadata

The uwsgi buffer size was too small to account for large headers in requests with datatables query parameters. This issue is resolved by increasing the buffer size.  See docs: https://uwsgi-docs.readthedocs.io/en/latest/ThingsToKnow.html

Close #24

tutordiscovery/templates/discovery/build/discovery/Dockerfile

@@ -58,4 +58,5 @@ CMD uwsgi \
     --single-interpreter \
     --enable-threads \
     --processes=2 \
+    --buffer-size=8192 \
     --wsgi-file course_discovery/wsgi.py