Add possibility to mount a tmpfs volume to /dev/shm to avoid issues like
[this](https://github.com/docker-library/postgres/issues/416). To achieve that
two new options were introduced:
* `enableShmVolume` to PostgreSQL manifest, to specify whether or not mount
this volume per database cluster
* `enable_shm_volume` to operator configuration, to specify whether or not mount
per operator.
The first one, `enableShmVolume` takes precedence to allow us to be more flexible.
removing parts of config.
* chaning secret name pattern to make things shorter.
* Move section on self building docker image.
* Fix typo.
* Bump image.
* bump version for pdb fix.
* Changes in regards to review.
* Fix xhyve driver link.
* Move to new api, remove service account, not needed for minikube.
* Changed minimal manifest and example to use right file.
* Added service account for operator again, it is needed in pods anyways later.