Tweak the styling of the login widget. Dont clobber the rounded
corner behind it, and use a pointer cursor on the sign out
bit.

Review at http://gwt-code-reviews.appspot.com/795801

Review by: jlabanca@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@8637 8db76d5a-ed1c-0410-87a9-c151d255dfc7