Policy: where should binaries go

E.g. if a environment should contain a binary which should be available to python apps which run in that enviroment. E.g. [pandoc](https://github.com/conda/conda-recipes/tree/master/pandoc), whichshould be available for `nbconvert` or `pypandoc`.

This isn't handled consitently in the conda-recipe repo: a linux is isnatleld into `PREFIX/bin`, but windows sometimes into `LIBRARY_BIN` and sometimes into `SCRIPTS`.

In my windows python, `LIBRARY_BIN` is automatically added to the path (`os.environ["PATH"]` contains `LIBRARY_BIN`) but not scripts. For this I would prefer that such apps go into `LIBRARY_LIB`, so that they are available even if I don't activate the env but call python there directly.

I've no clue how Linux/OSX handle this...