title: Codeception DB module: invalid config details
body: <p>I am quite new to Codeception but have not found much online about this issue either. 
  So, I am testing my API and this is my <code>codeception.yml</code>:</p>
  
  <pre><code>actor: Tester
  paths:
      tests: tests
      log: tests/_output
      data: tests/_data
      support: tests/_support
      envs: tests/_envs
  settings:
      bootstrap: _bootstrap.php
      colors: true
      memory_limit: 1024M
  extensions:
      enabled:
          - Codeception\Extension\RunFailed
  modules:
      config:
          Db:
              dsn: ''
              user: ''
              password: ''
              dump: 'tests/_data/dump.sql'
              populate: false
              cleanup: false
              reconnect: true
  </code></pre>
  
  <p>Pretty basic, right?</p>
  
  <p>To continue with, this is the <code>api.suite.yml</code> contents:</p>
  
  <pre><code>class_name: ApiTester
  modules:
      enabled:
          - \Helper\Api
          - REST:
                  url: http://localhost:8000/v1
                  depends: PhpBrowser
                  part: JSON
          - Db:
                  dsn: ''
                  user: ''
                  password: ''
                  dump: 'tests/_data/dump.sql'
                  populate: false
                  cleanup: false
                  reconnect: true
  </code></pre>
  
  <p>Straightforward too, I guess.</p>
  
  <p>Because I want to hide the login credentials, I put them in <code>_bootstrap.php</code>: </p>
  
  <pre><code>\Codeception\Configuration::$defaultSuiteSettings['modules']['config'] = [
      'Db' =&gt; array(
          'dsn' =&gt; 'mysql:host=' . getenv('CODECEPTION_DB_HOST') . ';dbname=' . getenv('jupix_branch_dev'),
          'user' =&gt; getenv('CODECEPTION_DB_USER'),
          'password' =&gt; getenv('CODECEPTION_DB_PASS'),
          'dump' =&gt; 'tests/_data/dump.sql',
          'populate' =&gt; getenv('CODECEPTION_POPULATE'),
          'cleanup' =&gt; getenv('CODECEPTION_CLEANUP'),
          'reconnect' =&gt; getenv('CODECEPTION_RECONNECT'),
      )
  ];
  </code></pre>
  
  <p>However, when I try to run the tests I receive:</p>
  
  <pre><code>[Codeception\Exception\ModuleException]
    Db: invalid data source name while creating PDO connection
  </code></pre>
  
  <p>Quite stuck on this one.</p>
  
  <p><em>Update</em></p>
  
  <p>As a note, when I remove <code>- Db:</code> config from <code>api.suite.yml</code> then my suit is running but it fails at the point that <code>ApiTester</code> calls <code>grabFromDatabase</code>, which is ApiTester-specific function.</p>