Changed ComboBox Selection Style to better fit ListBox, ListView, etc. style

Changed ComboBox Selection Style to better fit ListBox, ListView, etc. style

-) Foreground AccentSelectedColorBrush when selected
-) Background AccentBrush when selected
-) Background AccentColor3 when mouseover
Fixed the vertical alignment of the WindowsCommands

If the maximize, minimize and close buttons were hidden, the vertical
alignment of the WindowCommands was not centered
Merge pull request #463 from flagbug/windowcommands-fix

Fixed the vertical alignment of the WindowsCommands
Merge pull request #450 from stefan-schweiger/patch-3

Changed ComboBox Selection Style to better fit ListBox, ListView, etc. style
Overrode the ListView's original template to enable styling of the Disabled state.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	MahApps.Metro/Styles/Controls.ComboBox.xaml
Merge branch 'working'

Conflicts:
	MahApps.Metro/Styles/Controls.ComboBox.xaml
Merged with style from MetroComboBoxItem that are in the remote master branch