Pluggable Authentication/Authorization Mechanism

[eolivelli]

In order to integrate the web application with existing products we need to enable the host application to use its own authentication mechanism even for BKVM.

Proposals:

1. implement some sort of Single Sigle On, or at least the ability to recognize the status of the logged user on the host application (reading the same cookies?)
2. implement a pluggable authentication mechanism

In the case of Apache Pulsar Manager option 2) will be complex because it supports lots of authentication mechanisms.

I would go for 1)

[eolivelli]

@sijie @tuteng PTAL