Merge pull request sumocoders#54 from zeauw/master

Added the crmGetRelationships method

Merge pull request sumocoders#53 from jonasdekeukelaere/fix-products-…

…on-invoice-line

Fix use statement for Product in InvoiceLine

Merge pull request sumocoders#47 from wesleylancel/deal-reason-refused

Add reason refused field to deal

Merge pull request sumocoders#42 from doodhout/master

added property 'subtitle' to InvoiceLine (corrected)

Merge pull request sumocoders#43 from sumocoders/send-invoice

Add a method to send an invoice.

fix bug where product id's weren't added to invoice lines

allow us to link products to an invoice line

Added products

Merge pull request sumocoders#38 from sumocoders/more-style-fixes

Add more code style fixes.

Merge pull request sumocoders#37 from sumocoders/add-invoice-commentn

Allow us to add comments to an invoice.