Updates all relveant classes to work with new Monal APIs and to work
with the latest changes to the Data package.
Merge branch 'master' of https://github.com/juice49/Monal-Pages into juice49-master

Conflicts:
	src/controllers/FrontendPageController.php
Merge branch 'juice49-master'
Page types repository orders by name when retrieving.
Fixes bug in PagesAJAXController when ordering pages.
Changes the PagesRepository validation to all mutliple pages with the
same name.
Updates FrontendPage model to use the DataSets's new prepareValuesForOutput()
method.
Updates PagesRepository validation to allow a more diverse range
of charecters to be used for it's name.
Adds additional methods to the MonalFrontendPage class.
Removes redundant use statment.
Removed a page's URL property and replaces it with a URI property.
Updates all methods that set/retrieve this property and updates all
classes the reference it.
Changes if comparison logic for the buildPageHierarchy() method.
Basic monal-sitemap implementation