Add Rake task to get Spotify access token

For faster local debugging by hitting the Spotify API via curl commands.

Rakefile

@@ -8,3 +8,23 @@ namespace :generate do
     puts SecureRandom.hex(64)
   end
 end
+
+namespace :spotify do
+  desc 'Get an access token for the specified user_name'
+  task :access_token, [:user_name] do |t, args|
+    user = User.find_by_user_name(args[:user_name])
+
+    unless user
+      puts "No user exists with user_name #{args[:user_name]}"
+      next
+    end
+
+    if user.update_spotify_tokens
+      puts "#{user.user_name}'s access token:"
+      puts user.spotify_access_token
+    else
+      puts "Failed to update #{user.user_name}'s access token:"
+      puts user.errors.full_messages.join(', ')
+    end
+  end
+end