Namespace fixes in multi-word *test.clj files

Summary: These fixes resolve "invalid namespace" exceptions thrown by the Clojure compiler when project test files are run.

Updated multi-word *test.clj files (e.g.  to use valid Clojure namespaces in
function calls.

Also updated namespace declarations (e.g. "(ns my_project.test)" -> "(ns my-project.test)") for the following files:
crypto_square_test.clj
difference_of_squares_test.clj
largest_series_product_test.clj
robot_simulator_test.clj