add a convention for loading yaml config files from the classpath

[c-horn]

Instead of explicitly including the config file with spark-submit like:

spark-submit --file config_file.yaml data-validator.jar --config config_file.yaml

If the yaml file is already on Spark's driver classpath (for instance in a jar compiled from a resources/ directory included in a package added with --packages or --jars), you can reference it:

  --config classpath:/config_file.yaml

[dougb]

Please add at 2 tests for reading config off of classpath (success and failure), and update README to document new behavior.

[c-horn]

@dougb ^

[dougb]

I asked @c-horn to make one more change here to add some text about the classpath config feature.

[dougb]

👍

[colindean]

I don't have merge perms on this repo (yet). Can you add me or merge it, @dougb or @phpisciuneri?

[phpisciuneri]

@colindean we were trying to get the CI sorted out. Sorry for the delay.

@dougb @c-horn merging branch master into this PR didn't seem to trigger any action. The status check is still waiting for compile data-validator action. I am just going to merge. We can sort this out with a fresh PR.