A few style cleanups in MesosContainerizer.
A few style cleanups in MesosContainerizer.

Review: https://reviews.apache.org/r/51389

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