Fixed tests to pass in Python 3.

The simmetrica code uses a dictionary and range in a few places. This causes some small Python 3 compatibility issues.
    
The order of the dictionary isn't guaranteed, but the test expects it to be. This fix changes that so it works in Python 3 by sorting the result before comparing.
    
In Python 3 range() doesn't return a list, but rather returns a range object. Therefore, to make this work in both versions the test makes sure its a list before comparing.

This change requires #9.