Release 2.0-rc6

• Upgrade GWT Version to 2.8.1
• Added validate() to the base MaterialWidget and recursive validation. (Thanks @BenDol ).
• Added HasValue on MaterialImage.
• Added more helper methods to ViewPortHelper - isMobile(), isTablet() and isLaptop().
• Fixed MaterialToast resetting id when using custom classes (Thanks @xliii ).
• Corrected some Vietnamese translations for DatePicker (Thanks @Cupi ).
• Added jquery warning (#636) & fixed tabindex issue with MaterialDatePicker. (Thanks @BenDol ).
• Remove MaterialNoResult to Addins component and refactor to 'MaterialEmptyState'.
• Can now provide your own version of JQuery using JQueryProvider: (Thanks @BenDol ).

<replace-with class="com.client.MyJQueryProvider">
  <when-type-is class="gwt.material.design.client.JQueryProvider"/>
</replace-with>
MyJQueryProvider extends JQueryProvider.

• Use LeafValueEditor in AbstractValueWidget. (Thanks @BenDol )
• Implements HasNoSideNavSelection to MaterialNavMenu.
• Added method setActive(int index) to automatically select sidenav items.
• Create FullscreenMixin and apply to existing core / addin widgets.
• Apply change on MaterialSlider - that has also fullscreen mode capability.
• Added Junit Test for recent Modal.setFullscreen(boolean).

Bug Fixes:

• #635, #637