Add wm_state attribute to launchables

This pull request adds the wm_state attribute to launchables.  Each provider defines wm_state for its own launchables when it retrieves them.

For Conductor (right now), no state information is retrieved; thus wm_state is simply set to ACTIVE.  For Openstack, wm_state is set to ACTIVE if the image status is active, and INACTIVE otherwise.

This allows us to filter on launchables in a generic way.  This methodology should also help us with provider_applications, as the winged monkey workflow can work directly on an application's wm_state, allowing a unified workflow.

This addresses issue #98