Sync JHU cache

[krivard]

After #325 is fixed, we'll need to sync the JHU cache with the API again. Procedure is:

• Use a script like this to download the current contents of the JHU signals in the API
• Become the indicators user on the primary server
• Replace the contents of ~indicators/runtime/jhu/cache/ with the freshly-downloaded copy
• Optionally upload the cache to S3 (the indicator will process one file at a time, so a mass upload might be faster)
• Copy params.cache-repair.json to params.json
• Run the JHU indicator (env/bin/python -m delphi_jhu)
• Wait until Automation is not currently running an upload cycle (scheduled for :50 every hour)
• Copy receiving/*.csv to /common/covidcast/receiving/jhu-csse/
• Copy params.production.json to params.json