[XEROSUGAR-254] - Enable CRM users to get the Xero Invoice link for invoices where it isn't already available, so that they can then forward that link to clients for payment.
[XEROSUGAR-255] - Mark invoices as sent in Xero when invoice is created in SugarCRM so that Xero will send invoice reminders
[XEROSUGAR-258] - Remove unnecessary options from the 'Invoice Type' field so that invoice creation is simpler.
[XEROSUGAR-246] - Fixed issue relating to currency when creating an invoice
[XEROSUGAR-250] - Fixed issue when hitting API limit
[XEROSUGAR-251] - Sync invoices on initial sync failed
[XEROSUGAR-261] - Xero Contact Name not displaying correctly