Fix duplicate "-e" environment variables option in Docker::run.
Fix duplicate "-e" environment variables option in Docker::run.

Review: https://reviews.apache.org/r/36179

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