title: Magento's formatDate helper prints incorrect date
body: <p>In a Magento template, i am picking a Date which is stored as a product attribute. That's the config (setup ressource):</p>
  
  <pre><code># Attribute default config - every property can be overridden
  $defaultAttributeConfig = array(
      'input'                     =&gt; 'date',
      'type'                      =&gt; 'datetime',
      'backend'                   =&gt; 'eav/entity_attribute_backend_datetime',
      'frontend'                  =&gt; 'eav/entity_attribute_frontend_datetime',
      'visible'                   =&gt; true,
      'visible_on_front'          =&gt; false,
      'required'                  =&gt; false,
      'user_defined'              =&gt; false,
      'used_in_product_listing'   =&gt; true,
      'group'                     =&gt; $defaultAttributeGroup,
      'global'                    =&gt; Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_STORE,
      'apply_to'                  =&gt; 'bundle,simple,configurable',
      # Other
      'default'                    =&gt; null,
      'source'                     =&gt; null,
      'searchable'                 =&gt; false,
      'visible_in_advanced_search' =&gt; false,
      'filterable'                 =&gt; false,
      'filterable_in_search'       =&gt; false,
      'comparable'                 =&gt; false,
      'is_html_allowed_on_front'   =&gt; true,
      'is_configurable'            =&gt; false,
      'used_for_sort_by'           =&gt; false,
      'position'                   =&gt; 0,
      'used_for_promo_rules'       =&gt; false,
  );
  
  $installer-&gt;addAttribute(
      $productEntityTypeId,
      'time_lapse_begin',
      array_merge($defaultAttributeConfig, array(
          'label'     =&gt; 'Time-lapse begin',
          'sort'      =&gt; 10,
      ))
  );
  </code></pre>
  
  <p>In my template file i am processing the date for debugging purposes as follows:</p>
  
  <pre><code>&lt;?php list($timeLapseBegin, $timeLapseEnd) = array($_product-&gt;getTimeLapseBegin(), $_product-&gt;getTimeLapseEnd()); ?&gt;
  
  &lt;?php if ($this-&gt;validateDate($timeLapseBegin)): ?&gt;
  
  &lt;p&gt;
      Origin Date &lt;?php echo $timeLapseBegin ?&gt;&lt;br /&gt;
      Full Date: &lt;?php echo Mage::helper('core')-&gt;formatDate($timeLapseBegin, 'full'); ?&gt;&lt;br /&gt;
      Long Date: &lt;?php echo Mage::helper('core')-&gt;formatDate($timeLapseBegin, 'long'); ?&gt;&lt;br /&gt;
      Medium Date: &lt;?php echo Mage::helper('core')-&gt;formatDate($timeLapseBegin, 'medium'); ?&gt;&lt;br /&gt;
      Short Date: &lt;?php echo Mage::helper('core')-&gt;formatDate($timeLapseBegin, 'short'); ?&gt;
  &lt;/p&gt;
  
  &lt;?php endif; ?&gt;
  </code></pre>
  
  <p>Unfortunately, the output isn't as expected:</p>
  
  <pre><code>Origin Date 2013-01-01 00:00:00
  Full Date: Montag, 31. Dezember 2012
  Long Date: 31. Dezember 2012
  Medium Date: 31.12.2012
  Short Date: 31.12.12
  </code></pre>
  
  <p>As you can see, the Origin Date reads 2013/01/01, but Magento's helper formats it to 2012/12/31 - this is a day before and not expected...</p>
  
  <p>Any help or hint is appreciated. Thank you in advance!</p>