attempt to prevent circular dependency exceptions during tests (http://robots.thoughtbot.com/how-to-fix-circular-dependency-errors-in-rails-integration-tests)
fixed a couple of RuboCop offenses
an experiment to make tests run reliably using Timecop
[Finishes #84032884] Updated javascript on activites page to account for different element name of activites public radio button.
updated participant sign in authorization
  * participant cannot log in if they don't have an active membership
[Finishes #84330270]
undo failed Timecop experiment
remove 'Remember me' for Participants [Finishes #83687588]
updated dummy schema
enable adding icon to homescreen in mobile [#82660530]
version 1.5.18
modify url helpers due to breakage in tfd app
version 1.5.19
remove unused template
fix viewing of video slides in lessons [#84082410]
version 1.5.20
removed destroy dependency on tasks for user [Starts #83684764]
updated version [#83684764]
updated version
updated all User authorization [Finishes: #82524638]
updated version and changelog