Bug 20312: Add a link to last consulted patron

Bug 20312: Add a link to last consulted patron

This new feature adds a link to the last patron consulted
in the staff site. It uses cookies to save this information.
When a staff site user accesses a patron record, the ID, name
and card number of the patron will be saved in the cookie.

To test:
1- Apply the patch
2- Go to a patron details' page
4- Go to another page
4- Verify that the link "Last patron" appears on the top-right
   corner of the screen
5- Click on the link
6- Verify that you are at the patron's checkout page
7- Click on the "X" button next to the "Last patron" link
8- The link should be gone
9- Go to another page
10- The link shouldn't appear (until the next patron detail's
    page)

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>