EOD check in.
Refactors taxation context and tax methods to allow for tax estimates.  This is required by some 3rd party tax providers.
Merge pull request #787 from rustyswayne/1.4.0

Refactors taxation context and tax methods to allow for tax estimates
More work on the Avalara AvaTax provider.
Merge pull request #788 from rustyswayne/1.4.0

More work on the Avalara AvaTax provider.
Sales (orderlist.html & order.list.controller.js): Modified pagination functionality to use the perPage version of GetAllInvoices. Re-wired the GetFilteredInvoices function to use the QueryResult model.
Merge remote-tracking branch 'merchello/1.4.0' into 1.4.0