Renames the 'plist_filename' attribute to 'domain' [#66031656]

In the world of plists and defaults this notion is called a domain.  The domain
happens to be used for the plist filename but is used for more than that as
well.
Adds recipe to adjust the font size [#66031656]

- Adds new dependency on the osx cookbook in order to use the osx_defaults LWRP
- Includes in default recipe
- Backfills documentation on 'domain' property