provisioner/juju/provisioner: testing that deploy method logs its actions
api/app: removed deploy logic from clone handler.

Also simplifying the handler tests by using fake provisioner.
testing/provisioner.Deploy: writing action log in writer

This helps testing.

Also commenting juju provisioner test that ensures command execution
order
provision/lxc: added Deploy method to provisioner
provision/juju: writing logs to receive io.Writer instead of creating one
api/app.cloneRepository: writing logs in instance of LogWriter