View Source Upgrading to 2.0

A 2.0 release was published with a minor breaking change. We decided to vendor NimbleOptions (copy their code into our codebase) so that we could make some necessary modifications to it. What this means for users is primarily that:

1. we no longer depend on NimbleOptions
2. if you are matching on NimbleOptions.ValidationError you will need to update your code to match on Spark.Options.ValidationError