Update Node.JS and Ruby Dependencies (#617)

* Gemfile[.lock]: Update rails to 5.2.4.2

Also update its dependencies, as required.

* Gemfile[.lock]: Update grape and grape-swagger

Also update their dependencies, as needed.

* Gemfile[.lock]: Update activeadmin

* Gemfile: Pin sprockets to "< 4"

The 4.x major version upgrade requires some configuration changes.

Pinning keeps the app from breaking when doing `bundle update`.

* Gemfile.lock: Update all packages

* yarn.lock: Update all packages

Gemfile

@@ -1,18 +1,18 @@
 source 'https://rubygems.org'
 ruby '2.5.8'
 
-gem 'rails', '5.2.2.1'
+gem 'rails', '5.2.4.2'
 
-gem 'activeadmin', '~> 1.4.1'
+gem 'activeadmin', '~> 2.1'
 gem 'bootsnap', require: false
 gem 'bootstrap-sass', '>= 3.4.1'
 gem 'bugsnag'
 gem 'coffee-rails', '~> 4.2'
 gem 'country_select'
 gem 'devise', '~> 4.6'
 gem 'geocoder', '~> 1.2.1'
-gem 'grape', '1.1'
-gem 'grape-swagger', '~> 0.31'
+gem 'grape', '~> 1.3.0'
+gem 'grape-swagger'
 gem 'grape-kaminari'
 gem 'haml'
 gem 'high_voltage', '~> 3.0.0'
@@ -29,6 +29,7 @@ gem 'rack-jsonp'
 gem 'rakismet'
 gem 'sassc-rails'
 gem 'simple_form', '~> 5.0'
+gem 'sprockets', '< 4'
 gem 'turbolinks'
 gem 'uglifier', '>= 1.3.0'
 gem 'webpacker', '~> 4'