Percentage of Affordable Units Calculated Incorrectly

[dnardelli]

Describe the bug
The Affordable Units total while 'creating a development' does not include 'Unknown' units into the total, creating incorrect percentages.

Steps to reproduce

1. Go to 'https://www.massbuilds.com/map/developments/create'
2. Click on 'Create Development'
3. Scroll down to 'Development Type'
4. Click on 'Residential'
5. Scroll down to 'Affordable Units'
6. Enter '1' into all fields including 'Unknown Units'

Expected behavior
The total number of affordable units at the top right of this box should give '5 units', and the percentage for each 1 should correspond to that total (20%). Unknown should count towards the total, and have a percentage in relation to new total.

Desktop (please complete the following information):

• OS: [Windows 10 Pro]
• Browser [Chrome]
• Version [1803]