Dialer: improve letters' readability

Change "sans-serif-light" to "sans-serif" and make color a bit darker.

PSs: Resolve conflicts

Change-Id: I14449f99cdff8efbdcfc1910fe91fe5539f971fe

Conflicts:
	res/values/colors.xml

Change-Id: I72b63e2366a9967f086032396ec1ab19889e67a0