README shows parens as optional on @*rule_variable declarations

[ryboe]

Without the parens on @numeric_rule_variable, the object is not a function and doesn't have a __name__ attribute. The README should emphasize that the parens are required. Otherwise, this happens:

  File "/usr/local/share/.virtualenvs/lib/python2.7/site-packages/business_rules/variables.py", line 35, in wrapper
    func = _memoize_return_values(func)
  File "/usr/local/share/.virtualenvs/lib/python2.7/site-packages/business_rules/variables.py", line 63, in _memoize_return_values
    @wraps(func)
  File "/usr/local/lib/python2.7/functools.py", line 33, in update_wrapper
    setattr(wrapper, attr, getattr(wrapped, attr))
AttributeError: 'TransactionVariable' object has no attribute '__name__'

[gregeinfrank]

@y0ssar1an This was fixed in #17

This will be in the next release when it happens.

@akurihara - can you please push a new release?