Explicitly call with Spree namespace.
Fixes to Spree::TaxCloud#destination_address

* Refer to ::TaxCloud::Address rather than TaxCloud::Address
* taxcloud_usps_user_id.present? because it can be ""
* TaxCloud::Address is initialized with lowercase symbols
Only calculate eligible adjustments.
Merge pull request #21 from rterbush/eligible-adjustments

Eligible adjustments
Fix removing items from cart when tax adjustment exists.
Merge pull request #30 from jdutil/2-0-stable

Fix removing items from cart when tax adjustment exists.
Add line item association.
TaxCloud Savon SOAP client should be a class variable to avoid fetching WSDL file every time we make a new Lookup or Capture call
don't update adjustments for meaningless tax changes
Merge pull request #31 from jdutil/prelaunch

Add line item association.
Merge pull request #32 from dotandbo/2-0-stable

Prevent SOAP client from re-fetching WSDL file from network for every request
Make TaxCloud Savon SOAP client a class variable
Merge pull request #34 from freerunningtechnologies/column_scale_fix

Fix precision, scale of decimal columns on cart_item
Performance improvement in tax_cloud_transaction.rb
Remove attr_acessible. fixes #40
Use update_column in rails 4.
Cleanup before pulling in JDutil pr
merged JDutil changes
fixes #40 #43
Allow ~> 2.1.x