Add ifnone param to detect to handle missing branch

In response to [#4](https://github.com/hackling/morse/issues/4)

Added the [_ifnone_](http://www.ruby-doc.org/core-2.1.2/Enumerable.html#method-i-detect) parameter to the detect call so an empty Hash is returned (instead of nil) when no matching branch was found. The parameter needs to respond to `#call` (Method or Proc) so an inline lambda was used.