excludeDependencies: excludeAll at the project level

```scala
excludeDependencies += "org.apache.logging.log4j"
excludeDependencies += "com.example" %% "foo"
```

In the first example, all artifacts from the organization `"org.apache.logging.log4j"` are excluded from the managed dependency.
In the second example, artifacts with the organization `"com.example"` and the name `"foo"` cross versioned to the current `scalaVersion` are excluded.

yeah... i'd instead go the other way.  Let's see how much of that API we can clean up internally and instead unify on something that's easier to grok when you read it.

Basically, i'd rather go consistent when it's not a choice between confusion and understanding. In that case, let's start moving the confusing code into something less confusing.