Add Support for cap_add & cap_drop

[gitlawr]

Fixes #575
This commit Add support for cap_add & cap_drop which maps to
Pod.Spec.Container.SecurityContext.Capabilities.Add/Drop
Added unit tests for ConfigCapabilities function
Updated conversion.md on support for these keys

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[gitlawr]

signed

[kadel]

Woow, that was quick!
Thank you @gitlawr for great PR.

[cdrage]

Wow! This is great!

LGTM. Thanks @gitlawr this will come in-time for the 0.6.0 release today 💯

[gitlawr]

Glad to hear that 😉