Enable controller HA as default

[Vadim Raskin <ra...@gmail.com>]

Hi everyone,
after much of effort was done by several people to make controller HA work
(kudos to Christian, Jeremias, Tyson and others) we are finally going to
enable it as default (
https://github.com/apache/incubator-openwhisk/pull/2994) in the open
repository. What does it mean?
* Edge is going to dispatch requests to all (2) controller instances in
round robin
* Controller clustering will be enabled, which means that the load balancer
state will be replicated using akka clustering
* Since we already have 2 controllers deployed in Travis we will test both
of them when new PRs are created
There could be some implications of clustering depending on the deployment
model you are using. They are documented here:
https://github.com/apache/incubator-openwhisk/blob/master/docs/deploy.md
In case you use default parameters from open and don't want to use the a.m.
HA property you need to explicitly unset the properties of controller.ha
and controller.localBookkeeping.
Thank you.
regards, Vadim.