title: How to always use ignore-platform-reqs flag when running composer?
body: <p>On my local machine, I have php v7.0.3. A project of mine has a dependency on php v5.5.</p>
  
  <p>So as expected, a simple run of <code>composer install</code> crashes:</p>
  
  <pre><code>Your requirements could not be resolved to an installable set of packages.
  
    Problem 1
      - This package requires php ~5.5 but your PHP version (7.0.3) does not satisfy that requirement.
  </code></pre>
  
  <p>I know I can ignore the platform via:</p>
  
  <pre><code>composer install --ignore-platform-reqs
  </code></pre>
  
  <p>yet I often forget to add the flag. Yet since the application runs inside a docker container, a mismatching php can install the dependencies just as fine.</p>
  
  <p>So I am wondering if there is a way to make my local composer always assume <code>--ignore-platform-reqs</code> in order to not having to type it.</p>
  
  <p>I like to avoid setting an alias and have it work on composer config level.</p>