7 collapse same domain

This is to add feature #12. I'd like to get some feedback before rolling this out as I wasn't sure about a lot of things. This is how it looks atm:
Default view:
![image](https://f.cloud.github.com/assets/1301962/1557867/dc05c47c-4f49-11e3-9466-b8bdb2fdc742.png)
Click on the first item and expand it:
![image](https://f.cloud.github.com/assets/1301962/1557871/06fc6c44-4f4a-11e3-8b98-0cadf24747bc.png)

some notes:
- the 2nd item in the default view is a single page and is not clickable/expandable. So the feed is made up of a mix of groups of pages (that are expandable) and single pages. 
- pages are in a group together if they are next to each other in the feed and have the same domain. There isn't a check for closeness in time or anything like that, although there could be.
- hovering over the time on the right side on an expandable row prints 'Total time spent is 13 min on Nov. 6...', so here you can know the total amt of time spent on that domain.

Please let me know your thoughts!