Added tests for following scenarios:
* deploy session
* list all deployments
* list deployments (in a specific environment)
* list a specific deployment's statuses
Added application_catalog_client methods for following functionality:
* list all deployments
* list deployments (in a specific environment)
* list a specific deployment's statuses
Change-Id: I0ac1b2a6216fd1794ba06ee0b26e6c2c90118526