Removed the unnecessary space in middleman config.rb.
Removed the unnecessary space in middleman config.rb.

Review: https://reviews.apache.org/r/47903/

Gilbert88/mesos,zmalik/mesos,Gilbert88/mesos,kaysoky/mesos,abudnik/mesos,chhsia0/mesos,abudnik/mesos,jpeach/mesos,asamerh4/mesos,kaysoky/mesos,verizonlabs/mesos,reneploetz/mesos,reneploetz/mesos,craimbert/mesos,asamerh4/mesos,andschwa/mesos,Aman-Jain-14/customizedMesos,andschwa/mesos,verizonlabs/mesos,asamerh4/mesos,jpeach/mesos,Gilbert88/mesos,asamerh4/mesos,Gilbert88/mesos,neilconway/mesos,kaysoky/mesos,kaysoky/mesos,yuquanshan/customizedMesos,craimbert/mesos,gsantovena/mesos,yuquanshan/customizedMesos,gsantovena/mesos,jpeach/mesos,dforsyth/mesos,andschwa/mesos,zmalik/mesos,gsantovena/mesos,gsantovena/mesos,neilconway/mesos,kaysoky/mesos,abudnik/mesos,reneploetz/mesos,asamerh4/mesos,zmalik/mesos,craimbert/mesos,dforsyth/mesos,zmalik/mesos,Aman-Jain-14/customizedMesos,asamerh4/mesos,zmalik/mesos,jpeach/mesos,chhsia0/mesos,jpeach/mesos,gsantovena/mesos,craimbert/mesos,dforsyth/mesos,dforsyth/mesos,reneploetz/mesos,Aman-Jain-14/customizedMesos,andschwa/mesos,neilconway/mesos,verizonlabs/mesos,jpeach/mesos,yuquanshan/customizedMesos,zmalik/mesos,Gilbert88/mesos,asamerh4/mesos,yuquanshan/customizedMesos,verizonlabs/mesos,reneploetz/mesos,kaysoky/mesos,gsantovena/mesos,neilconway/mesos,Gilbert88/mesos,neilconway/mesos,chhsia0/mesos,andschwa/mesos,abudnik/mesos,yuquanshan/customizedMesos,neilconway/mesos,yuquanshan/customizedMesos,verizonlabs/mesos,abudnik/mesos,Aman-Jain-14/customizedMesos,chhsia0/mesos,zmalik/mesos,chhsia0/mesos,dforsyth/mesos,dforsyth/mesos,reneploetz/mesos,kaysoky/mesos,verizonlabs/mesos,Aman-Jain-14/customizedMesos,Aman-Jain-14/customizedMesos,andschwa/mesos,craimbert/mesos,craimbert/mesos,chhsia0/mesos,Aman-Jain-14/customizedMesos,jpeach/mesos,verizonlabs/mesos,abudnik/mesos,Gilbert88/mesos,andschwa/mesos,reneploetz/mesos,craimbert/mesos,gsantovena/mesos,chhsia0/mesos,abudnik/mesos,dforsyth/mesos,neilconway/mesos,yuquanshan/customizedMesos