Settings: Accessibility - We want consistence...change from CheckBoxPreference to SwitchPreference

Google changed it on all main settings. It does not make sense that on system settings
the old CheckBoxes are still used.

This commit changes all CheckBoxes in accessibility settings to Switches

Same needs to be done for Date and Time and Developer Settings

Change-Id: I335285270bcb8fa5e6e86f32a099f901e6d44d29

Conflicts:
	res/xml/accessibility_settings.xml
	src/com/android/settings/accessibility/AccessibilitySettings.java