catch exception when trigger type is invalid or null;
workshop docs
Finish updating the ConfigCatalogs tutorial.
Add link to TDSConfig repository.
Small tweaks to NcML examples for tutorial.

Update to data file we have and fix typos. Still need to track down
hwave_4D.nc.
Finished CatalogPrimer.html
* Deleted CatalogPrimerW.html. All of its content has been moved to CatalogPrimer.html.
Merge branch '4.5.4' of https://github.com/Unidata/thredds into 4.5.4