Consider using app-guid to identify bind !host rather than binding_id

[micahlee]

Presently the service broker creates a !host record when an application is bound to the service using the binding_id value (guid).

This may not match the user expectations when attempting to connect Conjur policy IDs (GUIDs) to the cloud foundry names for the corresponding apps. The Organizations and Spaces map directly, however, the Application GUID is not used, but rather its binding id.

This issue is to consider using the app_guid rather than the binding_id when creating the Conjur Host.