Added a ReadOnlyFill property

ReadOnlyFill property for when you want the control to be readonly, but
still want a custom colour showing rather than the default black.
Fixes Bug #47 - provides ability to tie into back button and optionally cancel form closing event
Added contribution page
Added fix to avoid live tile flipping when only one item is availble
Merge pull request #178 from dotMorten/master

Don't animate live tile if Count =< 1
Modifications to dropdown sample for font variations
Merge branch 'dev' of https://github.com/timheuer/callisto into dev
Fix #167: Added listener for Window SizeChanged which should cause light dismiss surfaces to dismiss.
Fix #171: Enhancing flyout/IHM placement logic to adjust for more visible input areas in certain scenarios.
Merge https://github.com/lprichar/callisto into lprichar-master
Fix #47: Adding BackTapped event to be able to leverage
Fix #156: Changing 'tapped' to click so that it maps for touch and keyboard
Merge branch 'master' of https://github.com/ScottIsAFool/callisto into ScottIsAFool-master
Merging ReadOnlyFill for Rating control
Fix #136 by unsealing CustomDialog
Fix #140 Guard against if the parent is not a Flyout
Revising versions in deployable packages
Fix #184: Template binding H/V scroll properties for SettingsFlyout
Rev'ing changelog/versions
Fix #189,#190 for localization and SettingsFlyout