2.0.0.0-dev57

* Fixed bugs:
  * Fixed [MAP]: "Click for price" link is broken on the category page
  * Fixed tax rule search on the grid
  * Fixed redirect on dashboard if "Search", "Reset", "Export" buttons are clicked on several pages
  * Fixed switching user to alternate store-view when clicking on the Category (with Add Store Code to Urls="Yes" in the config)
  * Fixed printing Order/Shipping/Credit Memo from backend
  * Fixed 404 Error on attempt to print Shipping Label
  * Fixed duplication of JavaScript Resources in head on frontend
  * Fixed inconsistency with disabled states on Configurable product page in the Plushe theme
  * Fixed 3D Secure Information absence on Admin Order Info page
  * Fixed possibility to download or revert Backup
  * Fixed session fixation in user registration during checkout
  * Fixed fatal error during login to backend
  * Fixed inline translations in the Adminhtml area
  * Fixed partial refunds/invoices in Payflow Pro
  * Fixed the issue with ignoring area in design emulation
  * Fixed order placing with virtual product using Express Checkout
  * Fixed the error during order placement with Recurring profile payment
  * Fixed wrong redirect after customer registration during multishipping checkout
  * Fixed inability to crate shipping labels
  * Fixed inability to switch language, if the default language is English
  * Fixed an issue with incorrect XML appearing in cache after some actions on the frontend
  * Fixed product export
  * Fixed inability to configure memcache as session save handler
* GitHub requests:
  * [#406](https://github.com/magento/magento2/pull/406) -- Remove cast to (int) for the varch increment_id
  * [#425](https://github.com/magento/magento2/issues/425) -- Installation of dev53 fails
  * [#324](https://github.com/magento/magento2/pull/324) -- ImportExport: Easier debugging
* Modularity improvements:
  * Removed \Magento\App\Helper\HelperFactory
  * Removed the "helper" method from the abstract block interface
  * Layout page type config moved to library
  * Design loader moved to library
  * Theme label moved to library
  * Remaining part from Adminhtml moved to the appropriate modules. Adminhtml module has been eliminated
  * Core Session and Cookie models decomposed and moved to library
    * \Magento\Stdlib\Cookie library created
    * Session Manager and Session Config interfaces provided
    * Session save handler interface created
    * Session storage interface created, session does not extend \Magento\Object anymore
    * Session validator interface created
    * Session generic wrapper moved to library
    * Messages functionality moved from the Session model as separate component, message manager interface created
    * Sid resolver interface created to handle session sid from request