rework ssl pass through interface

[geemus]

We have accumulated a mix of different parameter names and usage patterns in our ssl passthrough stuff. None of it matches the underlying ssl implementation (which might be fine), but there is also a mix of file and data allowed. We would probably be better off doing a rethink on this to make it all be consistent and picking just one style (file vs data) to support throughout. Note that this would likely require deprecation warnings and backwards-compatibility bits for an extended period before we could safely retire the old interface.