Set up test module on local

[PennyQ]

Set up nbody code on virtual env is not easy, so leave travis-ci for future. Currently write a test code for running simulation on local machine, will be done after #23

[PennyQ]

see #29

[PennyQ]

@maxwelltsai Running test will give an error as:

>                   sim_inst.id = id
E                   AttributeError: 'NoneType' object has no attribute 'id'

../../simon.py:177: AttributeError

The reason is in simon.py the self.module_dict = self.register_modules() does not get assigned correctly, the module_dict list is empty. Do you know how this would happen?