Improved comments in agent.
Improved comments in agent.

Review: https://reviews.apache.org/r/55300/

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