Make browser toasts show source room

The source roomname doesn't appear on chrome's toasts, but it could/should.

This change should fix #808

![jabbr-toast](https://f.cloud.github.com/assets/1271535/494382/d1c64976-bb99-11e2-80c4-76d0b898e88e.png)
Appears when user CJM posts that message to room Whiskey.

Also, truncates when the toast titles are otherwise too long:
![jabbr-toast-truncate-new](https://f.cloud.github.com/assets/1271535/494491/94d99410-bb9d-11e2-9275-4394a449f2dc.png)

Also, shows just the username if that takes up all the space:
![jabbr-toast-truncate-new2](https://f.cloud.github.com/assets/1271535/494495/9fb5a806-bb9d-11e2-9d6b-ac261fb8d9c2.png)