Add specs for `Module`-based behavior object

[edisonywh]

Currently, the tests are pretty simplistic in that it always çreate the Behavior Object as a class. Logically (untested) it should more or less work the same for Module, but it's good to add specs for some sanity check and to verify that it actually works.

When specs are added and it is verified to work, we could also add this into the README detailing that both Module and Class would work.

See #13