title: simple_form selected: by name
body: <p>I have a simple_form collection which contains a list of languages. I want to select 'German' by default, but the selected: option in simple_form requires an id. I could obtain the id of 'German' but would hope that wasn't necessary.</p>
  
  <pre><code>= f.association :language, selected: // not sure what to put here
  </code></pre>
  
  <p>This works, but stinks (I will NOT be using such atrocious code):</p>
  
  <pre><code>= f.association :language, selected: Language.where("name = 'German'").first.id
  </code></pre>
  
  <p>I would hope for something like:</p>
  
  <pre><code>= f.association :language, selected: { |lan| lan.name == 'German' }
  </code></pre>
  
  <p>Every example I've found during the last hour involves the id. Not one example of how to select via the name.</p>