Make credits configurable on Stanford CME

* Assumes cert_data stanza now has additional "CREDITS" subdict, with a
  key "COUNT" and a key "TYPE". These are interpolated directly onto the
  certificate.

@stvstnfrd, please. @caesar2164, fyi.

My hope, @sarina, is not only that this will help us, but that it will make the cme template marginally more useful to members of the open source community.... (But firstly it helps us by letting us support courses worth lots of different credit values.)
Yeah... perhaps it's not internationalizable...
"English uses a fairly common pattern – subject (S) verb (V) object (O): The dog (S) bit (V) the postman (O). But other languages do things very differently. In Jiwarli, an indigenous Australian language, the components of the English sentence ‘This woman kissed that bald window cleaner’ would be rendered in the following order: _That this bald kissed woman window cleaner_."

Language is super fascinating....