Changes the style of the username label.
Changes the style of the username label.

Background of the label changed to the 35% opaque black color. Label
alignment changed to be left oriented. Also gradient part was added to
the end of the label.

BUG=chromium-os:5756
TEST=Go to login screen (non-first login). Notice changes of the label
appearance.

Review URL: http://codereview.chromium.org/3604008

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@61993 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser