Fixes bench tests under JRuby
Fixes bench tests under JRuby

* It appears that require 'minitest/spec' pulls in the stdlib version of
  minitest, as opposed to the > 2.1 gemified version required by
  mini_shoulda. This causes conflicts and bizarre errors messages. Since
  mini_shoulda pulls in 'minitest/spec' as well (but the correct
  version), this line can simply be removed.

StreetEasy/dalli,mperham/dalli,dplummer/dalli,IFTTT/dalli,jcxplorer/dalli,eileencodes/dalli,mcansky/dalli,mdesjardins/dalli,dblock/dalli,petergoldstein/dalli,wjordan/dalli,arthurnn/dalli,tlemburg/dalli,murtuzakz/dalli,akihiro17/dalli,ScotterC/dalli,kei-s/dalli,jkriss/dalli,hirocaster/dalli,retailnext/dalli,nitinstp23/dalli,mumoshu/dalli,cjbottaro/dalli,mrb/dalli,tmm1/dalli,Tapjoy/dalli,chendo/dalli,seamusabshere/dalli,indirect/dalli,alindeman/dalli,petergoldstein/dalli,stefanwille/dalli,reverbnation/dalli,indabamusic/dalli,alevy/dalli,jwinter/dalli,uzzz/dalli,rafaelfranca/dalli,vipulnsward/dalli,exact/dalli,glenngillen/dalli,linyows/dalli,cluesque/dalli,freeatnet/dalli,sanemat/dalli,steveklabnik/dalli,eagletmt/dalli,nbibler/dalli,joshwlewis/dalli,mcka1n/dalli,shaiguitar/dalli,ahawkins/dalli,jonhinson/dalli,sandys/dalli,hbu50/dalli,pjg/dalli,leonid-shevtsov/dalli,jaxi/dalli,danielribeiro/dalli,jjb/dalli,godfat/dalli,dannyfallon/dalli,naseem/dalli,dtakahas/dalli