title: spring boot: add new yml files to application config
body: <p>i want developers to be able to locally override some configuration properties. (let's say we work on google drive and everyone should test it on its own account). 
  i don't want to override properties using command line (because it has to be set inside every IDE configuration and on every CLI run).</p>
  
  <p>what i want is: application should use all the standard spring boot config files (<code>application.yml</code> etc) and also look for e.g. <code>local.yml</code> (on the classpath) or some file inside <code>user.home</code>. and those additional files should override other settings.</p>
  
  <p>how to add new <code>yml</code> resources and order them correctly?</p>
  
  <p>edit: i know spring's default orders and locations. question is about adding <strong>new</strong> ones</p>