change the default action context to omit api key

[Rodric Rabbah]

Hi,

I'm looking for feedback on the following issue:
https://github.com/apache/incubator-openwhisk/issues/4226

Actions receives the API key in the environment even if it is not
necessary. This should not be the default behavior. With the issue I'm
proposing that we flip the default and provide an annotation on the action
to enable the key forwarding to preserve existing behavior.

Additionally We currently created the following context:
{
       "api_host": process.env['__OW_API_HOST'],
       "api_key": process.env['__OW_API_KEY'],
       "namespace": process.env['__OW_NAMESPACE'],
       "action_name": process.env['__OW_ACTION_NAME'],
       "activation_id": process.env['__OW_ACTIVATION_ID'],
       "deadline": process.env['__OW_DEADLINE']
}

https://github.com/apache/incubator-openwhisk/blob/da21c9fe49b2ae72c95b6866b30d984c65253724/core/invoker/src/main/scala/org/apache/openwhisk/core/containerpool/ContainerProxy.scala#L565-L571

Should we hide the namespace, action name and activation id as well?

-r