title: Fresh rails app defaulting to Postgres instead of SQLite3
body: <p>I've just installed rbenv, ruby 2.2.3 and rails 4.2.4 for the first time on this machine. I've started my rails application with no change to any of the code, just the default generated documents from using <code>rails new .</code>, I then started the server with <code>rails server</code>.</p>
  
  <p>When hitting <code>http://localhost:3000</code> I'm getting the following error:</p>
  
  <p>"Specified 'postgresql' for database adapter, but the gem is not loaded. Add <code>gem 'pg'</code> to your Gemfile (and ensure its version is at the minimum required by ActiveRecord)."</p>
  
  <p>I've got postgres installed from a previous project with Node, but my database.yml still reads as you'd expect from a new application:</p>
  
  <pre><code># SQLite version 3.x
  #   gem install sqlite3
  #
  #   Ensure the SQLite 3 gem is defined in your Gemfile
  #   gem 'sqlite3'
  #
  default: &amp;default
    adapter: sqlite3
    pool: 5
    timeout: 5000
  
  development:
    &lt;&lt;: *default
    database: db/development.sqlite3
  
  # Warning: The database defined as "test" will be erased and
  # re-generated from your development database when you run "rake".
  # Do not set this db to the same as development or production.
  test:
    &lt;&lt;: *default
    database: db/test.sqlite3
  
  production:
    &lt;&lt;: *default
    database: db/production.sqlite3
  </code></pre>
  
  <p>I don't really want to use Postgres at the moment, I'm just starting out and I'd rather keep things simple with SQLite3 for a bit. Does anyone know what may be going on and what I could do to get it using SQLite3 so that this error stops?</p>