title: How to avoid composer form upgrading project dependencies (ex. laravel from 5.1 LTS)?
body: <p>I'm worrying about Laravel and long term support concepts, related to my application.</p>
  
  <p>Now I've developed my app on lrvl 5.2, but the LTS version is the 5.1.
  Since I'd like to have a long term supported framework as my application basement, I wonder if it's the case to downgrade to 5.1. No features problems should arise for my specific app. But this is another story... not the topic of this question.</p>
  
  <p>Secondly I don't see how to tell composer to stick to laravel 5.1 then, 
  i.e. when I'll run a composer update avoid updating the laravel 5.1 version.</p>
  
  <p>Should I also worry about tweaking composer from updating the dependency packages? </p>