Catch Exceptions of all sort from dashboard server code and provide proper report of a problem

[GoogleCodeExporter]

Much of the dashboard server code throws IllegalArgumentException when some 
problem is detected with user input.  A number of these propagate to the GWT 
client pages, but GWT has problems with handling these exceptions 
(serialization errors), so a 500 error results leaving the user wonder what 
went wrong.  (Latest example - NCEP SLP not available for 2014, and Camilla 
attempted to add a 2014 cruise.  NCEP SLP has been updated to include 2014, but 
this problem will come up again.))

All exceptions need to be caught and turned into error responses to these pages 
instead of relying on GWT to properly handle the exception.  (Might be fixed in 
latest GWT, but better if we do not rely on this.)

Original issue reported on code.google.com by [email protected] on 20 Jan 2015 at 8:29