Creating ensemble submission

Steps for creating and submitting a real-time ensemble forecast. This set of steps needs to be performed every Monday evening after 5pm (or whenever the last models get pushed) and before 11:59pm.

1. Make sure you are on the master branch of the cdc-flusight-ensemble repository.
2. Pull all recent commits.
3. Check to see if all component models have current forecasts. If not, the ensemble will still build, but send email to nudge contributors.
4. Run the make-real-time-ensemble-forecast-file.R script. This should generate a set of all ensemble forecast files, including one that is saved in model-forecasts/submissions/target-based-weights, and a multi-page PDF file with plots in the model-forecasts/submissions/target-based-weights/plots/ folder.
5. Look at the plots to make sure nothing looks terribly out of alignment.
6. Commit the plots file and all new ensemble files to your local git repository.
7. Push all files to the master branch. Include the words "deploy" in the commit message so that Travis CI rebuilds the visualization.
8. Email the submission file to the CDC.
9. Tweet out new forecasts!