[TR #49] Create a function to find all Clojure versions in the database
Amar Singh coauthored this commit.
Creates edu.unc.applab.clem.db.exception/fetch-clojure-versions which returns all clojure versions in the database as a list of strings. It does not attempt to sort or organize them in anyway, but does make sure there are no duplicates.
This commit also adds basic tests for the method.