Update to work with Clojure 1.7

[mshenfield]

Upgrade clojail to work with the latest stable release of Clojure (1.7 as of today). This lays the groundwork for TryClojure to use Clojure 1.7, as mentioned in Raynes/tryclojure/issues/53.

[mshenfield]

The only breaking change is an update to the threading macro in Clojure 1.6, which, instead of expanding

(macroexpand '(-> x inc dec)) to (dec (clojure.core/-> x inc))

as in 1.5, outputs a complete result instead of a recursive one in 1.6+

(dec (inc x))

Updated the tests to use an argument to macroexpand that doesn't conflict across versions.