Fix of the issue astashov#41

The error of missing self.debugger_id was happened due to incorrect
returning of control from ruby_debugger.rb when start command is given.
Adding of stripping of leading/trailing whitespaces in comparement fixed
that issue.

bin/ruby_debugger.rb

@@ -108,7 +108,7 @@ def handle_queue
         log("Putting message to rdebug-ide: #{message}")
         @rdebug.puts(message)
         # Start command doesn't return any response, so send message immediatly
-        send_message if message == 'start'
+        send_message if message.strip == 'start'
       else
         send_message
       end