Loan Contract Word Documents; updated script code to better handle Interest Rate Table premiums

The script code behind the Loan Contract Word Documents have been updated to better handle Interest Rate Table premiums (Startup and Ongoing).

They were using the InterestRate property, when they should have been using the InterestRatePremium property.

Note, the InterestRate property also holds the Premium (for backwards compatibility) - so this change has been made to save confusion.

The following Documents have been updated:

"Loan_Contract_NZCCCFA" has been updated to version 1.05 on 21/08/2017.
"Loan_Contract_NZCCCFA_RC" has been updated to version 1.04 on 21/08/2017.