Fix request specs, failings down to 1

Add en.yml file with devise namespace entries. It feels odd to have
the devise namespace on spree core locale file since users can opt to
use other auth strategies or even have an already devise auth model.
Keeping those entries on spree core may confuse / override users
existing app devise locale entries

Fixes #85
Bumping Versionfile for 2-0-stable
master branch now depends on spree 2.1.0.beta [Fixes #95]
Versionfile clean up
Bump gem version
Speeling [Fixes #90]
use Spree.t on order.state [Fixes #96]
UserMailer inherit from Spree::BaseMailer

No need for check if the constant is defined since at this point users
tracking spree_auth_devise 1-3-stable must also be tracking spree
1-3-stable

Fixes #97
Dont call load_order for index action.
Add travis config

This is useful for those who want to fork this project and be able to run the
tests.
Use correct path_prefix so that URLs are correct