EOF on exit

Avoid EOF error on server.stop


```
/Users/iRyusa/.rvm/gems/ruby-2.0.0-p247/gems/ladle-0.2.0/lib/ladle/server.rb:281:in `readline': end of file reached (EOFError)
	from /Users/iRyusa/.rvm/gems/ruby-2.0.0-p247/gems/ladle-0.2.0/lib/ladle/server.rb:281:in `watch'
	from /Users/iRyusa/.rvm/gems/ruby-2.0.0-p247/gems/ladle-0.2.0/lib/ladle/server.rb:276:in `block in start'
```