frameworks/base: Update quick launch shortcut icons/resources

Update the existing icons and add "xxhdpi" versions created
from a vector template. This commit cleans also the resource
files a bit up.

Screenshot: http://goo.gl/6CrMYr

Change-Id: I45abee5cf13cd239eb5b4402019afac28d6d5952

Conflicts:

	core/res/res/drawable-mdpi/ic_navigation_ring_blank_activated.png
	core/res/res/drawable-mdpi/ic_navigation_ring_blank_normal.png
	core/res/res/drawable-mdpi/ic_navigation_ring_ime_switcher_activated.png
	core/res/res/drawable-mdpi/ic_navigation_ring_ime_switcher_normal.png
	core/res/res/drawable-mdpi/ic_navigation_ring_screenshot_activated.png
	core/res/res/drawable-mdpi/ic_navigation_ring_screenshot_normal.png
	core/res/res/drawable-mdpi/ic_navigation_ring_silent_activated.png
	core/res/res/drawable-mdpi/ic_navigation_ring_silent_normal.png
	core/res/res/drawable-mdpi/ic_navigation_ring_sound_on_activated.png
	core/res/res/drawable-mdpi/ic_navigation_ring_sound_on_normal.png
	core/res/res/drawable-mdpi/ic_navigation_ring_vibrate_activated.png
	core/res/res/drawable-mdpi/ic_navigation_ring_vibrate_normal.png
	core/res/res/values/dimens.xml
	core/res/res/values/symbols.xml