Destinations Page

Added a destinations page, which lists all invoices from delivery windows in the same time frame
Re-grouped delivery windows by date and time.
Re-styled summaries page to accommodate this change.

Summary Page (updated):
![ios simulator screen shot feb 9 2014 9 33 21 pm](https://f.cloud.github.com/assets/2354636/2121954/d1158e20-91fd-11e3-9c9c-eda3d95a4a3b.png)

Destinations Page (new):
![ios simulator screen shot feb 9 2014 9 33 26 pm](https://f.cloud.github.com/assets/2354636/2121957/e3028066-91fd-11e3-95e0-90fa87e6296d.png)

A few design decisions:
- For re-grouping the delivery windows, I re-grouped them in two layers (date & time) in code for flexibility. However, when displaying them in the summary page, I only re-group them in one layer (time) for better viewing.
- I removed timestamp associated with each delivery window as they are no longer necessary (can be determined from the heading).
- For the destination page, I named the url `invoices` because I want to aggregate the invoice links that are now under each delivery window into this page. *I need comments on this*.