pin-sample

The new system uses 2 branches instead of 3.
They are `master` and `run-test-suite`.

Pinning is no longer in tsv file.

There are pin files for each supported master commit in the `env` dir.
A pin file names the yaml-test-suite repo and data branch commit to use.
It also lets you blacklist/whitelist which tests to use.

The pin files can be symlinks.
They can also include (source) and override other files.

To specify pinning info for a PR you put it in your commit message.
See ReadMe.md for more details.