Rename MWTemplateParameter* classes to MWParameter*

* The name was getting super long, and the Template prefix doesn't
  appear to be important.
* Soon we will add a placeholder class, which would have been
  MWTemplateParameterPlaceholder, but now just MWParameterPlaceholder
  which seems a little less ridiculous.

Change-Id: Ie2dfe0d4c7b960cd554f89fa6340173e8786c88a
Merge "Rename MWTemplateParameter* classes to MWParameter*"