s/identifier/entity/ in ->naming-strategy

clojure.java.jdbc expects :entity not :identifier see: https://github.com/clojure/java.jdbc/blob/java.jdbc-0.2.3/src/main/clojure/clojure/java/jdbc.clj#L288
Merge pull request #145 from djwhitt/patch-1

s/identifier/entity/ in ->naming-strategy