Add environment file

[jakirkham]

Fixes https://github.com/conda-forge/cdt-builds/issues/32

Refactors dependencies into an environment file to make it easier to get started.

Please see the repo readme for directions on how to make PRs on this repo.

Checklist:

• [ ] if you have added a CDT, it appears in the cdt_slugs.yaml file and you have rerun the script python gen_cdt_recipes.py.
• [ ] if you have changed the CDT generator code (rpm.py), you have bumped the build number in conda_build_config.yaml and have remade all of the recipes via running python gen_cdt_recipes.py --force
• [ ] if you have added a custom CDT recipe, you have added the name of the CDT with custom: true in the cdt_slugs.yaml file.
• [ ] all CDT recipes have build number set by {{ cdt_build_number }} for old-style/legacy CDTs or {{ cdt_build_number|int + 1000 }} for new-style CDTs
• [ ] if you see a warning about a CDT not having a license, you have added the license_file key in the cdt_slugs.yaml file with the path to the appropriate license in licenses/

NOTE: If you make any changes to cd_slugs.yaml, you need to reun the generator code via python gen_cdt_recipes.py. Add the --fast option to make this go more quickly.

[jakirkham]

One thought might be to use this to create a totally new environment just to ensure this file provides a complete list of what's needed. Though I haven't done that here as that may be more of a change than we want.

[beckermr]

Go for it! If you'd like to merge now, that's great too!

[jakirkham]

Either way. Happy to do in a new PR as well 🙂

[beckermr]

I'm happy with this as is.