Find a better way to calculate LMI

[robase]

The current LMI calculation relies on a lookup table compiled from googling around various websites. I'm not sure if insurance agencies publish their LMI premiums publicly, there seem to be a lot of LMI calculators out there but little info on how they derive their numbers.

To fix:

• lookup table caps out at house prices >$1m currently
• avoiding the use of a lookup in favour of an equation would lower the maintenance pain when values change over time