Introducing silent_stream

ActiveSupport’s Stream Silencing - Without ActiveSupport SilentStream is an extraction of some parts of ActiveSupport’s Kernel Reporting Core Extentions. Since July 2014 silence_stream, silence_stderr, capture, silence, and quietly have been deprecated because they are not thread safe. See that discussion in the PR where it all went down. I rely on them a lot in single threaded code, and so I plan to keep them alive.