Added file/fid/usage to cp_theme function #2719

 Did a little refactoring.  in_array is much cleaner than a handful of or'ed equals conditions.

 Now for scholar-3.9!
Missed a path.  #2719

Did I mention the original was hard to read?
Merge pull request #4275 from openscholar/2719-usage_theme-3.9

Added file/fid/usage to cp_theme function #2719