Make Etymology configuration work

* Remove XHTML hack for ICmObject types in favor of
  cssClassNameOverride
* Fix tests which relied on the hack
* Add etymology overrides to the shipped configurations
* Generate xhtml for plain string types when they are found
  in the model
* Add test for Source under Etymology

Change-Id: Ic5406bf581cf0b19abe9c98fcf98cc86d1c7eadf