Removed duplicate error messaging in Docker::create.
Removed duplicate error messaging in Docker::create.

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