Added a benchmark to test the performance characterstics of fakeweb vs webmock.
Added a benchmark to test the performance characterstics of fakeweb vs webmock.

ihassin/vcr,Shopify/vcr,davidbebb/vcr,ZmagoD/vcr,benjaminoakes/vcr,allyapp/vcr,allyapp/vcr,nishanbose/vcr,chriswoodrich/vcr,Shopify/vcr,irfanah/vcr,mcfiredrill/vcr,ihassin/vcr,travis-repos/vcr,ZmagoD/vcr,mcfiredrill/vcr,asymmetric/vcr,cemo/vcr,chriswoodrich/vcr,myronmarston/vcr,myronmarston/vcr,nishanbose/vcr,cemo/vcr,intfrr/vcr,intfrr/vcr,irfanah/vcr,asymmetric/vcr,davidbebb/vcr