Add Juju PaaS as a VIM

The following fields are mandatory:

--account_type = paas
--config = '{paas_provider: juju}'

In case of PaaS VIM, Kafka message
is not sent to LCM.

Change-Id: Ib53a953706d05659aee4fdf0b147623cb5347cfd
Signed-off-by: Patricia Reinoso <patricia.reinoso@canonical.com>