Fix Gunicorn 20 error

This fixes two errors, one where we were not importing HTTPerror
appopriately in tasks.py which led to the app crashing and a second
error introduced by upgrading gunicorn. Gunicorn was upgraded to version
20 from 19.9 which was a major version upgrade and introduced a breaking
change. The change is documented by this issue on the git repo benoitc/gunicorn#2159
it is related to removing an eval statement so we can no longer have
gunicorn call a function to create our app. We have gone with a solution
introduced in this issue, to call the create_app function and then
export a variable where this application is saved. We then call
this variable in our Procfile where we run our server using Gunicorn.

This should fix our issue for now, and if gunicorn fixes the issue
in the libarary then we could always revert but I think this should
work going forward.

Procfile

@@ -1,4 +1,4 @@
-web: pipenv run gunicorn "app:create_app()" --workers 8 --log-file -
+web: pipenv run gunicorn "app:bsafe" --workers 8 --log-file -
 worker: pipenv run flask worker --threads 1
 periodiq: pipenv run flask periodiq
 

app/__init__.py

@@ -1 +1 @@
-from .app import create_app
+from .app import bsafe

app/app.py

@@ -38,3 +38,5 @@ def configure_logging(app):
         logging.FileHandler(f"{app.config['LOG_FOLDER']}/log.log"),
         logging.StreamHandler()
     ])
+
+bsafe = create_app()

app/tasks.py

@@ -17,6 +17,7 @@
 import os
 import datetime
 import requests
+from urllib.error import HTTPError
 from periodiq import PeriodiqMiddleware, cron
 from ergo_analytics import LoadElasticSearch
 from ergo_analytics import DataFilterPipeline