Remove references between User and Invoice in model
Remove references of 'owner' for invoices in db seed files
Remove references to 'owner' in Invoice, replace with "artifical" attribute getOwner()
Fix invoicesOfUser query method in Invoice
Fix UserTests
Fix routing conflict for Invoices#show
Fix client route
Remove delete tests for User. Not in spec
Fix failing Invoice test (testInvoiceDueDateShouldBeAfterDate)
Merge branch 'bindings-refactor' into develop