Change the base.rb active_shipping calculator to only do rate calculations for the stock_location
that is represented by the passed in object. We are dealing with Spree::Shipment and Spree::Stock::Package
objects only.

In researching this issue, it seems we are passing a Spree::Shipment object whenever promotion_adjustments
is called when adding items to the cart and on checkout, we are passing the Spree::Stock::Package object.

The crux of the change is at line 160 where I am limiting calculations to the object.stock_location_id
Fix calculator to use Package object as required in 2.0
Merge pull request #85 from rterbush/first-class-calc-port

Fix calculator to use Package object as required in 2.0
Clean up this condition a bit. We cannot deal with anything other than Spree::Shipment
and Spree::Stock::Package objects.
Merge pull request #84 from rterbush/splitship-calculator

Change the base.rb active_shipping calculator to only do rate calculations for the stock_location
We need to handle order objects being passed in as well and stock_location.id is available.
Merge pull request #88 from rterbush/splitship-order

We need to handle order objects being passed in as well
remove raise ShippingError from comput, fix #90

taken from commit 5150d1fd80f44e69464eccd9fd034657933d1d12 on 1-3-stable
Merge pull request #93 from rterbush/shippingerror

remove raise ShippingError from comput, fix #90
Update 2-0-stable tests so they at least run.

Help welcome to fix them now.
Merge pull request #95 from rterbush/tests-2.0

Update 2-0-stable tests so they at least run.
Spree::ActiveShipping::Base#compute should only ever take a Spree::Stock::Package object

Fixes #96

Conflicts:
	app/models/spree/calculator/shipping/active_shipping/base.rb
Make 'spree' line in Gemfile friendly to bundle.local configs

Conflicts:
	Gemfile
Begin putting in place a real testing framework for this extension

Conflicts:
	spec/models/active_shipping_calculator_spec.rb
Make active_shipping line in Gemfile friendly to bundle config local.active_shipping
Replace the stock_location_id instance variable.

Fixes #98
Only run 1.9.3 and don't spam IRC
Remove @stock_location variable after discussion in #98
Fix issue where shipping methods were not being registered

The 'descendants' method will return an empty array if the subclass files are not loaded first.

Fixes #101