This change removes the twitter authentication feature from the application.
It removes the `omniauth-twitter` gem and all related code from controllers, views, and tests. It also removes the twitter icon and environment variable settings.
We deprecated controller and view specs on the grounds that they were
brittle, and were a poorer measure of user experience than feature
specs. However, feature specs have their own problems: they're much
slower to run, and flakier (see #901). We also ran into a few cases
where feature specs erroneously passed because they were checking for
the presence of a string that occurred in the error page!
Hence, we're cautiously un-deprecating controller and view specs.
Fixes#1132
* FactoryGirl Changed to FactoryBot
file fix
changes based on comments received
Bundle Update on 2017-10-29
style update to align hash literal
added package-lock
* indentation fixes with rubocop
* name added to contributors
