contrib.gemfile in ddtrace-0.6.0

- old
+ new

@@ -5,8 +5,9 @@
 gem "elasticsearch-transport"
 gem "redis"
 gem "hiredis"
 gem "rack-test"
 gem "sinatra"
+gem "activerecord"
 gem "sidekiq"
 
 gemspec :path => "../"