Added support for reading multiple throwables

Doesn't it get used in this version: https://github.com/sbt/sbt-remote-control/pull/232/files#diff-db29c4e085b8f4c32553f20b38c780bcR79

It's following the exact same pattern as `resultWithCustomThrowable` except that the deserializers come from a set instead of one.  The use case is I'm going to generate this set once (for all Play exceptions) and use it.