Streamline CA and cert handling

[bikramnehra]

Currently, the service broker is generating its own CA and cert which is presented while communicating with any client trying to communicate with the broker:

https://github.com/appscode/service-broker/blob/master/chart/service-broker/templates/cluster-service-broker.yaml#L1-L5

This means that the client needs to have this CA in its trust store, which might not be desirable in some cases.

We need a better mechanism of handling certs, e.g one approach might be to provide an option to pass custom CA cert while performing the installation.

[weenxin]

I have the same problem too .