Relaxed error handling

[the-toster]

After several years of using this great library, I became to conclusion that *Server should not catch non-\Twirp\Error exceptions-).

I'm using it along with laravel framework, and it already has own exception-handling part, and believe it's framework responsibility to handle application-level exceptions.
Framework can generate corresponding twirp-compatible responses using some library methods.

It will cover cases like this - #67

What do you think?