service/service_instance.go: getting units only once in BindApp
service/service_instance: stop using select and using wait group on BindApp
service/actions: creates action for adding an app to a service in the database
service/bind/bind_test: fixing bind test name
testing/provisioner: adding SetEnvs method to FakeApp
testing/provisioner: FakeApp now satisfies bind.App interface
service/actions: creates action to request service endpoint and set environment variables to the apps

Relates to #384