Unprefix linear-gradient
Unprefix transition
Fix transition's value in dashboard.css
Add unprefix user-select in "Photo - Capture" Extractor
Unprefix and update Notification

We should use latest W3C's Web Notifications,
instead of old Chromium's Desktop Notifications.
Update minimum_chrome_version from 23 to 26

Unprefix linear-gradient and transition are available in Chrome 26+.
Merge pull request #179 from syoichi/pr25-unprefix

Unprefix linear-gradient, transition, Notification