Expose ignore_eof option for Net::HTTP

[adamzapasnik]

The other day I discovered an ignore_eof setting that was added to Net::HTTP and Net::HTTPResponse in https://github.com/ruby/net-http/pull/15

Was wondering it makes sense for open-uri to expose setting ignore_eof via options or even setting it to false by default, but that's probably not backwards compatible, so it leaves us only the first solution?

wdyt?