Output correct EDN from API using pr-str.

Simply offering up a Clojure object to the toString gods results in a
representation that may have logic to it, but cannot be read back in by
cljs.reader/read-string (or, presumably, clojure.edn/read-string).

The core pr-str function generates a valid EDN string.
Fixes #2: Request and read EDN data instead of JSON.

raiseyourgame.lib.data/GET has been upgraded to accept :edn (default) or
:json media types, and automatically convert the response to the Clojure
or JavaScript data, respectively, unless the optional "raw" argument is
true. See the GET docstring.

Controllers and templates now use this new functionality to work with
Clojure data from end to end.