Specific support for Embedded Python

[kuszewski]

Embedded Python adds another wrinkle where a package may need to add python packages into the packages' installation directory (/zpm///python, for example). It should also feed this into the rest of the package installation process so that it's easy to set the pythonpath on the fly when loading these modules.

It should be easy and obvious how to handle this situation.

[isc-tleavitt]

Possible platform features coming at some point that could help with this, calling it blocked for now.

[isc-tleavitt]

ref: #773