Remove 'jasmine' gem

jasmine-rails still requires it as a dependency, but for some reason
running `rake jasmine:ci` produced test failures but
`rake spec:javascript` didn't.

Gemfile

@@ -248,7 +248,6 @@ group :development, :test do
   # PhantomJS driver for Capybara
   gem 'poltergeist', '~> 1.5.1'
 
-  gem 'jasmine', '~> 2.2.0'
   gem 'jasmine-rails'
 
   gem "spring", '~> 1.3.1'

Gemfile.lock

@@ -290,11 +290,6 @@ GEM
     i18n (0.7.0)
     ice_cube (0.11.1)
     ice_nine (0.10.0)
-    jasmine (2.2.0)
-      jasmine-core (~> 2.2)
-      phantomjs
-      rack (>= 1.2.1)
-      rake
     jasmine-core (2.2.0)
     jasmine-rails (0.10.8)
       jasmine-core (>= 1.3, < 3.0)
@@ -726,7 +721,6 @@ DEPENDENCIES
   hipchat (~> 1.5.0)
   html-pipeline (~> 1.11.0)
   httparty
-  jasmine (~> 2.2.0)
   jasmine-rails
   jquery-atwho-rails (~> 1.0.0)
   jquery-rails

lib/tasks/jasmine.rake

@@ -0,0 +1,12 @@
+# Since we no longer explicitly require the 'jasmine' gem, we lost the
+# `jasmine:ci` task used by GitLab CI jobs.
+#
+# This provides a simple alias to run the `spec:javascript` task from the
+# 'jasmine-rails' gem.
+task jasmine: ['jasmine:ci']
+
+namespace :jasmine do
+  task :ci do
+    Rake::Task['spec:javascript'].invoke
+  end
+end