Support watching multiple namespaces

[leochr]

We currently support watching a single namespace, own namespace and all namespaces in the cluster.

Adding support to watch a set of namespaces will benefit users who want to watch more than one namespace, but not the entire cluster.

[arthurdm]

I have confirmed this is needed for our next release, to support multiple kabanero configurations.

[navidsh]

Next version of Operator SDK will have support for watching multiple namespaces out of the box. Until it releases a new version, we can use a workaround for this.

To get around this, the operator can watch all namespaces, and filter events using the namespaces it's watching.

The operator will read a comma-separated list of namespaces from WATCH_NAMESPACE env variable.

[arthurdm]

awesome @navidsh! will we also update this page: https://github.com/appsody/appsody-operator/tree/master/deploy/releases/daily#installation?

[navidsh]

Good catch @arthurdm! I'll update that.

[navidsh]

Delivered. Closing.