Robust handling of missing ACE data in timeline

ACE data has not been flowing for at least 4 days since Dec. 22, 2012.  This causes program failure in make_timeline.py as noted in issue #10 as well as potential operational confusion.  This PR improves the handling of missing ACE data and adds infrastructure to test various missing data scenarios.    

- Instead of dropping bad ACE data at the point of reading in  values, leave the bad values there (as indicated by a negative value) and do downstream handling of bad values.
- Indicate bad or N/A values with bold red text in the state table.   If there is no average P3 from MTA then use 0.0 for fluence prediction but  show fluence as red.
- Plot bad ACE values so viewer can more easily see missing data.  This shows up as a vertical line to the bottom of the plot.