Merge pull request XeroAPI#97 from XeroAPI/xero-python-1.18.0

generates xero-python-1.18.0 from OAS 2.27.0

Merge pull request XeroAPI#96 from XeroAPI/lee-repeating-invoices-test

repeating invoices

Merge pull request XeroAPI#92 from XeroAPI/xero-python-1.16.0

generates xero-python 1.16.0 from OAS 2.23.0

Merge pull request XeroAPI#90 from XeroAPI/xero-python-1.15.0

generates xero-python-1.15.0 from OAS 2.22.0

Merge pull request XeroAPI#88 from XeroAPI/xero-python-1.14.0

generates xero-python 1.14.0 from OAS 2.21.0

Merge pull request XeroAPI#85 from XeroAPI/xero-python-1.13.1

generates xero-python 1.13.1 from OAS 2.19.3

Merge pull request XeroAPI#79 from XeroAPI/xero-python-1.13.0

generates xero-python-1.13.0 from OAS 2.18.0

Merge pull request XeroAPI#77 from XeroAPI/xero-python-1.12.0

generates xero-python-1.12.0 from OAS 2.17.4

Merge pull request XeroAPI#67 from XeroAPI/xero-python-finance-api-redo

generated from OAS 2.17.2

Merge pull request XeroAPI#64 from XeroAPI/xero-python-1.10.0

generates from OAS 2.17.1 minus finance API