Add footer.

On this footer, completed task and left task count is deisplayed.
Add #region

coverd UnCompletedCount by region.
Add Checkbox for select all.

Add Checkboc to select all todo. After that, add NotifyProperty into MainWindowViewModel.
Next step is to meka logic for check all checkbox in listbox.
implement isuues #3

Add "Select All" checkbox.
implement isuues #2

Add "Select All" checkbox.
Merge branch 'prototype' of github.com:hidari/WhatNeedToBeDone into prototype
change Listbox's BorderBrush

changed it's Listbox's border brush to Transparent.
Merge branch 'dev/borderTransparent' into prototype
Merge branch 'prototype'