Feature Request: Allow passing the security context

[pascalbe-dev]

Openshift requires running images as non root. Bitnami images support that by letting the user of a chart pass values to overwrite the security context settings. See within the postgres chart for example: https://github.com/bitnami/charts/tree/master/bitnami/postgresql

Passing security context options is not supported here, if I don't miss something here.

Therefore:
Would it be possible to allow the user of the chart to pass security context information?

[arcmmartins]

I have created a PR that implements this, could you please take a look @fuziontech? Thank you