add build date, modversion, in about menu

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 Changes to be committed:
	modified:   res/values/strings.xml
	modified:   res/xml/device_info_settings.xml
	modified:   res/xml/settings_headers.xml
	modified:   src/com/android/settings/DeviceInfoSettings.java

Change-Id: Ibcaa95385f604764e67ee0bb07fb400788a705db
add icon for launcher settings meu

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 Changes to be committed:
	new file:   res/drawable-hdpi/ic_settings_home.png
	new file:   res/drawable-mdpi/ic_settings_home.png
	new file:   res/drawable-xhdpi/ic_settings_home.png

Change-Id: I1a0c347174df111e82f3ad24e99c7366e90ca150