spec: selenium 2.40 firefox 2.70 upgrades

Change-Id: I1b07116abbc86fe72cc2bda571fc07c71c016d0c
Reviewed-on: https://gerrit.instructure.com/32573
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Shawn Meredith <shawn@instructure.com>
Product-Review: Shawn Meredith <shawn@instructure.com>
QA-Review: Shawn Meredith <shawn@instructure.com>
Tested-by: Shawn Meredith <shawn@instructure.com>