Use proper HTML5 API for all browsers

Chrome, Firefox, Safari, and Chromium all now conform to the same HTML5
Notifications API.  This commit make Salvager use them all in the same
way.

Also fixed the URL for the Salvager icon that was causing Kaspersky to
freak out.  It was still fetching it from drunkensailor.org.
Merge pull request #236 from aiannacc/fix-notifications

Use proper HTML5 API for all browsers