Fix a bug in environment module
Fix a bug in environment module

Global variable _environment should be declared before being used
in global_env function. This patch fixed this error.

Change-Id: I808aa4fe76851c33e2670b2c9b7c732992b27027

stackforge/senlin,tengqm/senlin-container,openstack/senlin,stackforge/senlin,tengqm/senlin-container,openstack/senlin,Alzon/senlin,Alzon/senlin,openstack/senlin