Relax constraint of max FAR being below 20

[hanase]

The proforma model allows FAR <= 20 (via this check). Our FLU allows FARs over 30. Leave it to the user to decide what the max FAR should be.

[jessicacamacho]

Thank you for this issue @hanase,

We have increased the maximum reasonable FAR value to 500. Please take a look at https://github.com/UDST/developer/compare/fixes_months_calculation, and let me know if you have any questions.

Jessica