Add Open in Xero / Unleashed links

We are now sending our URL to Xero so that you can open the originating CRM quote from the Xero invoice. This works really nicely.

We should have the same in our system (to open the xero invocie and ledger from our system). 

a) for a confirmed order, have an open link/url to open the order in unleashed, or invoice in Xero.

b) for a sales ledger, have an open link to Xero/Unleashed

c) for sales history, hyperlink the invoice no and order no.

NOTE - in all these cases, we need to create the link at the point we create the record, or store the system (xero, unleashed) against the transaction/ledger/order. We should not just assume that because you are linked to unleased that all invoices in your sales history, all confirmed quotes etc can be opened in unleashed using a URL and the id - if you have migrated from another system (sage 50 or pegasus say) then most of your data should NOT hyperlink to unleashed.

i.e. i think we should create new IntegrationURL field for each and populate this with the correct url at that point.