2020-05-28 Week of 5/21 release

Features

• Add research sign up link #172511640 (#1338)
• Remove text regarding optional attendance #172655306 (#1337)
• Replace income with availability #171215415 (#1326)
• Remove vendors footer and add SFDS link #169017078 (#1328)

Bugs

• Fix duplicate translations on listing #172950053 (#1340)
• Fix screen reader for nav bar #169027064 (#1336)
• Fix user proof not uploading #172114799 (#1330)
• Fix language selection on auto-filled application #171215415 (#1325)

Chores

• Bump https-proxy-agent from 2.2.1 to 2.2.4 (#1324)
• Bump puma from 4.3.1 to 4.3.3 (#1318)
• Bump nokogiri from 1.10.7 to 1.10.8 (#1317)