Added Menus interactors. Deleted MenuManager
Started to implement Areas interactors. Added GetAllBlocksInteractor and UpdateBlockInteractor
Added tabs to Pages interface (Content, Structure, Versions, SEO)
Added notifications after saving in Pages interface.
Added Structure tab to page interface
Added Area update form in Pages interface
Added CreateBlock and CreateArea interactors
Merge branch 'develop' - v0.3.0