Openshift/OKD related changes to helm charts

[fruboes]

This PR contains changes necessary to use qserv helm chart in Openshift/OKD. Each change/addition is guarded with a {{ if .Values.openshift }} conditional, with the controlling value set to false in top level values.yaml file. Three main problems are covered:

1. openshift/okd by default randomizes uid/gid with which container is executed and disallows hardcoded values, e.g. defined on Dockerfile level. To workaround this a service account is created along with SecurityContextConstraint allowing for specific gid/uid (1000) to be used. This service account is used for all types of pods (worker/czar/...) for which this is necessary
2. openshift/okd does not allow for modifications of files/directories of underlying container image. This is handled by adding emptyDir volumes where necessary
3. openshift/okd by default prohibits pod binding to ports <1024. This is handled by going with the port to higher value (e.g. 80 -> 8080) . Note: having Service with port <1024 (80 in our case) is OK.

Please let me know if this could be merged, i.e. if there is anything that needs to be changed.