Share the host's process namespace with the Bosh BPM container

[istvanballok]

When trying to create a Bosh release with BPM for telegraf, to collect the metrics of the bosh managed jobs on a VM, we noticed that the procstat input plugin does not work probably because the BPM container is hard coded to use a separate process namespace.

Falling back to the pure monit based approach does not feel right, so I report this github issue.

BPM configuration documentation: https://bosh.io/docs/bpm/config/
Slack discussion: https://cloudfoundry.slack.com/archives/C7A0K6NMU/p1589886990004800?thread_ts=1585645037.002900&cid=C7A0K6NMU

Idea: make it configurable like with docker: https://docs.docker.com/engine/reference/run/#pid-settings---pid

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this:

https://www.pivotaltracker.com/story/show/173019708

The labels on this github issue will be updated when the story is started.

[rkoster]

Fixed in #144