CFY-1215

Manually tested for basic functionality. Used https://github.com/achirko/cloudify-openstack-plugin/blob/dev/plugin.yaml as plugin definition and https://github.com/achirko/cloudify-openstack-plugin/blob/dev/blueprint.yaml as a base for testing.
I agree that should be done for the sake of consistency. But in general in python it's preferred to import modules instead of single functions/decorators or variables - it's improves code readability.