Support multiple input files

[adamrtalbot]

We could support multiple input files, so we could define resources separately and run individual bits based on what we need (i.e., only things that have changed). Care would need to be taken about order.

script.py --options orgs.yml workspaces.yml secrets.yml credentials.yml computeenvs.yml pipelines.yml launch.yml

Then re-run :

script.py --options pipelines.yml launch.yml

[ejseqera]

I'm now wondering how to handle this because currently, with little modification, we could support this so each yaml corresponding to a tw subcommand would be run as a method of Tower() and to build the resources correctly, there would have to be some order in the individual yamls you provide.

OR...based on #25...

We define a hierarchy built-in so the order of the individual yamls doesn't matter either.

Either way, I think it would be a good idea!

[adamrtalbot]

I feel like a hierarchy makes the most sense, then you can just scoop up any YAML and combine them. So twpy *.yml would be perfectly valid.