Updated to jazz 0.2.0 to update support for elixir 0.15.0

Jazz updated to 0.2.0 with support for elixir 0.15.0 to remove the warning about 0.14.2

Ran full testsuite, and everything passed:

Finished in 2.8 seconds (1.9s on load, 0.9s on tests)
237 tests, 0 failures