behave runner shadows stage feature

It's not possible to use stage feature on behave as behave_runner miss loading the right environment file

It always loads environment.py and should load the default stategy one

def load_hooks(self, filename='environment.py'):
    """
    Overrides parent "load_hooks" to add "self.__hooks"
    :param filename: env. file name
    """
    super(_RunnerWrapper, self).load_hooks(filename)

The fix : 
def load_hooks(self, filename='environment.py'):
"""
Overrides parent "load_hooks" to add "self.__hooks"
:param filename: env. file name
"""
super(_RunnerWrapper, self).load_hooks()