Minor spec changes

A few small changes to the specs.

1. Addressed deprecation warnings.  
2. Upgraded selenium webdriver version.
3. Added a 'js' flag to a feature spec

Note that while looking at these issues, I discovered that a recent change in spree_core appears to have caused a regression in the spree_auth_devise gem.  There is a failing spec on this gem that appears to be a result of this change to spree_core

In spree_core the created_by_id attribute was added to Spree::Order and is now being used to look up Spree::User.last_incomplete_spree_order.  But this attribute is not being set if the user authenticates after the current_order is created.  This looks like something that needs to be added to associated_user