Improvements to notifications:

Improvements to notifications:
---

Story:
https://www.pivotaltracker.com/story/show/75446202

Demo:
https://s3-eu-west-1.amazonaws.com/uploads-eu.hipchat.com/22685/874180/z6zerZbLOPCWjnP/notification_with_close.mov

- Removed automatic fadeout for notifications
- Added close button
- Display message after register on notification instead of inside modal dialog
- Fixed markup for confirm account modal dialo