naming mismatch: HandlerOpts vs NewServer / Server

[bgentry]

The standalone Handler type was renamed to Server as part of some refactoring in #108, as was the NewHandler constructor (now NewServer). However, the HandlerOpts type was not renamed. Prior to shipping the next release with a functional embeddable http.Handler interface, we should probably align these API names.

Agree @brandur? Do you think HandlerOpts should just become ServerOpts?

[brandur]

Yeah, should be ServerOpts.