Change method missing warning to debug

Previously a warning was given, but that gave output noise. Now the
message of an observer method missing is only given in debug mode.
Replace tork exec with call to CLIApp

Instead of running the shell script to start tork, require tork and use
Tork::CLIApp.
Change Dir.basename to File.basename
Only pass name of unknown event to Event class
Allow minor version of tork to be upgraded
Add echo event and conditions for parsing

The echo event can return multiple events, so allow the parser to do so.
Fix conductor spec by using gets method on IO
Add more useful debug to conductor
Fix IO in reader, to stop premature EOFs

EOFs were being given as a result of not keeping the error and in
streams open with Open3#popen3.