[WIP] Attach primary contact

[bernardeli]

Hi @iloveitaly,

I'm currently opening this pull request as a WIP to get your opinion on the design of #299 (disclaimer: I work with @jamesottaway)

Based on http://www.netsuite.com/help/helpcenter/en_US/srbrowser/Browser2016_2/schema/other/attachcontactreference.html?mode=package, I assume AttachContactReference is a record where the attributes include contact and contact role.

The customer is the object to be attached to the tuple contact + role.

Given the above, I came up with the following idea:

customer = NetSuite::Records::Customer.new(internal_id: 1)
NetSuite::Records::AttachContactReference.new(contact: { internal_id: 1 }, contact_role: { internal_id: -10 }).attach(customer)

Sorry for the lack of tests at this point. I spat out the ideas to get my head around and would appreciate an initial feedback before I clean it up and put some tests.

Thanks
Ricardo